EVO: Engine Control

IGNITION, COIL, PLUGS & VOES

Factory Ignitions

Electronic Ignition Systems

(1980 to 2003) Components include a timing rotor (timing cup), sensor plate or inductive pickup, ignition control module, ignition coil and spark plugs. For electronic advance, the inductive pickup generates TDC pulses that are sent to the solid state Ignition Control Module (ICM). The ICM computes ignition timing advance and coil dwell. A Vacuum-Operated Electric Switch (VOES) is used (since 1983) to switch between 2 different spark advance curves built into the ICM. 1) These advance curves where modified over the years as indicated by the Curve Letter (such as G, J, K, Q). The variation in the model numbers were sometimes to designate different terminations of the cable (such as direct wire or 7-pin plug or 8-pin plug).

The ICM for these years uses a Dual-Fire Spark system. The dual-encapsulated coil is fired by only one coil trigger wire from the ICM. This produces a spark on both plugs at the same time, regardless of which cylinder is currently under compression. Therefore, there is a dual-spark created when the front cylinder is near TDC and there is another dual-spark created when the rear cylinder is near TDC. (See coil information below)

The spark advance starting point can be altered by physically rotating the sensor plate in the “nosecone”.

Ignition Control Modules (Latest Known Superceded Version)
883 Models '86-'87 1100 Models
Year Part No Curve RPM Limit Part No Curve RPM Limit
1986 31410-91B G 6500 32410-91B G 6500
1987 32410-91B G 6550 32410-91B G 6500
883 Models 1200 Models
Year Part No Curve RPM Limit Part No Curve RPM Limit
1988 32410-91B G 6500 32432-91B J 6500
1989 32410-91B G 6500 32433-91A M 6250
1990 32410-91B G 6500 32433-91A M 6250
1991 32410-91B G 6500 32433-91A M 6250
1992 32410-91B G 6500 32433-91A M 6250
1993 32410-91B G 6500 32433-91A M 6250
1994 32410-94A G 6500 32433-94 M 6250
1995 32410-94A G 6500 32433-94 M 6250
1996 32466-95A R 6250 32465-95A Q 6250
1997 32466-95A R 6250 32465-95B Q 6250

The 1998-2003 Non-Sport model used an integrated ICM on the Sensor Plate. The 1998-2003 1200Sport model used a separate Ignition Control Module and the same Sensor Plate as the 1986-1997 models. The 1200Sport model pioneered the Single-fire Spark system and the Manifold Air Pressure sensor (MAP) for the future Sportster models.

Ignition Control Modules (Latest Known Superceded Version)
883 Models 1200 Models
Year Part No Curve RPM Limit Part No Curve RPM Limit
1998-2003 Exc 1200S 32466-98B ? ???? 32465-98B ? ????
1998-2003 1200Sport Model 32480-98A ? ????

The 1986-1997 Ignition Control Module was located under the
Triangle Cover on the left side of the bike next to the battery.


(2004-2006) The Ignition Control Module (ICM) became more capable and included a digital communications link (SDB) between itself, the Turn Signal Module and the Speedometer. This new Serial Data Bus (SDB), using an accessible data port on the side of the bike, also allowed the ICM to be dealer programmed for either 883 engines or 1200 engines.

The newly added Crankshaft Position Sensor (CKP) replaced the camshaft pickup as a more advanced means of sensing the engine revolutions and the new Manifold Air Pressure sensor (MAP) replaced the VOES as a more advanced means of sensing engine loads. The ignition system gives a spark near top dead center for starting. Then, at running RPM and loads above this, the system gives a spark advance that varies between 0 and 40. (For further information, see the section below titled: 2004-later Single-fire Spark Synchronization)

From this point forward, the Sportsters used a Single-fire Spark system, using two individual coil trigger wires to produce a spark on individual spark plugs, one at a time. (see coil information)

The Ignition Control Module for these years is programmable by the dealer to match the specific model bike, either 883 or 1200. It is mounted under the seat. The part number on the ignition module is really the version of the internal software that was last flashed into the module. The module may have started out as a 32478-04 module, but then the part number could be superceded with 32622-04C (the latest version) when a reflash was done to upgrade the module.


(2007 - 2013) With the implementation of Electronic Fuel Injection, the Electronic Control Module (ECM) is the heart of the ignition system. It obtains inputs and controls outputs as listed below. This expanded capability for the ECM allows it to be programmed in minute detail to account for changing conditions in the operating engine.

The ECM obtains input information from:

  • Manifold Air Pressure Sensor (MAP)
  • Crank Position Sensor (CKP)
  • Engine Temperature Sensor (ET)
  • Intake Air Temperature Sensor (IAT)
  • Oxygen Sensors in Exhaust (two) - (O2)
  • Throttle Position Sensor (TPS)
  • Vehicle Speed Sensor (VSS)

The ECM controls the following outputs:

  • Serial Data Bus (digital) for Turn Signal Module & Speedometer
  • System Power Control thru System Relay
  • Idle Air Control (IAC)
  • Fuel Injectors in Heads (two)
  • Coil Firing Sequence - Single-Fire using Encapsulated dual-coils


(2014-on) To further expand the computerization of the Sportster, the ECM was equipped with a Controller Area Network Bus (CANBUS) and the Body Control Module (BCM) was added. In general terms, the CANBUS replaced the digital communications between the smart controllers (in place of the Serial Data Bus) and allowed computerization of the handlebar controls, while the BCM replaced the Turn Signal Module and handled power distribution throughout the bike, including to the lights and other components. The BCM also eliminated all relays.

2004-later Single-fire Spark Synchronization

ECM - Electronic Control Module
The ECM is mounted under the seat. It computes the spark advance for proper ignition timing and fuel control based on sensor inputs (2004-2006 uses CKP & MAP; 2007-later uses CKP, TMAP, ET, TPS, HO2S). It controls the low-voltage circuits for the ignition coils and the injectors.

The ECM controls the dwell time for the ignition coil while taking into account the battery voltage. The programmed dwell is designed to give adequate spark at all speeds. The ECM has protection against transient voltages, continuous reverse voltage protection and damage due to jump starts. The ECM is fully enclosed to protect it from vibration, dust, water or oil. It is a nonrepairable item and if it fails, it must be replaced.

32-2 Flywheel
The left flywheel has 32 teeth positions - 30 teeth are evenly spaced around its circumference with two consecutive teeth missing (sync gap). In this configuration, the ECM determines engine position, engine phase and engine speed from the CKP sensor input. Phase (TDC compression) is determined by the ECM during startup and, when necessary, while running. No engine ignition events can occur until the ECM determines the relationship of the piston position to the crankshaft position. The following paragraphs (see note below) describe synchronization and phasing by the ECM to provide smooth operation of the engine at all speeds.

Crank Position Signal Synchronization
In the 32-2 crank configuration, crankshaft position is determined by the ECM finding the empty two-tooth sync gap in the CKP sensor signal. This is usually accomplished the first time the sync gap is encountered. The ECM monitors the CKP signal status every engine revolution. If the ECM determines synchronization is lost, it immediately terminates ignition events and synchronizes on the next occurrence of the sync gap.

Engine Phase
Phasing is accomplished by the ECM identifying a widening in the CKP signal caused by the deceleration of the crankshaft, as a piston approaches TDC on its compression stroke. Since the rear cylinder approaches TDC earlier than the front cylinder, engine phase can be readily discriminated. Phasing is normally accomplished on the first TDC cycle after engine synchronization. Once phased, the ECM can begin normal ignition events. If the ECM experiences a system reset or loss of synchronization while the engine is running it also loses phase.

When phase is lost one of the following occurs:

  • If an engine-not-running (Crank Mode) rpm is detected, the ECM executes the normal start-up phasing process.
  • If Engine Run Mode is detected, the ECM executes a running re-phase sequence.

The front cylinder is fired every engine revolution. The ECM monitors the power stroke after the fire event to determine if sufficient acceleration occurred to indicate the ECM fired on the compression stroke. When two valid power strokes are detected, the ECM locks phase and resumes normal ignition events.

Engine Run Mode
Many functions of the EFI system require an engine run mode determination. Engine run is determined by the level of engine rpm. Generally, the engine is considered to be running when engine rpm exceeds a minimum of 750 rpm.

(Note: Based upon the 2013 Sportster Models Electrical Diagnostic Manual, page 6-3)

Aftermarket Ignitions

1998-2003 1200S Model


2004-2006 All Models

This is only one of the many discussions of the TwinTec TC88A module - http://xlforum.net/forums/showthread.php?t=518158


Ignition Coils - Specs & Checks

(1986-2003 Evo)
The coil is a dual encapsulated unit with two coils in one housing. These coils are interconnected serially to produce a Dual-fire Spark system - The internal front and rear coils both fire at the same time which produces a wasted-spark on the cylinder that is not under compression. This coil has one trigger signal from the ICM which fires both front and rear coils simultaneously. The Primary windings of the coil are typically measured at 3-ohms.

(2004-later Evo)
The coil is a dual encapsulated unit with two coils in one housing. It uses a Single-fire Spark system - The internal front and rear coils each fire their spark plug independently (one cylinder at a time - no wasted spark) when that cylinder is under compression. This coil has a front & a rear trigger signal from the ICM.

(1998-2003 Evo Sport)
These Sport models use a quad encapsulated unit with two dual-coils in one housing. Using dual spark plugs in their heads, these models utilize a Single-fire Spark system - The internal front and rear coils are independent, only firing when their cylinder is under compression. Each (front or rear) dual-coil fires a dual-plug-set. This coil has a front & a rear trigger signal from the ICM.

Primary Tower-to-Tower Output
Years Part Number Ohms Connector Secondary Ohms Firing
86-03 31614-83A 2.5 - 3.1 2 Lugs 10,000 - 12,500 Dual-Fire
Both F&R Plugs
04-06 31655-99 0.5 - 0.7 (A-B or B-C) 3 Pin 11,000 - 15,000* Single-Fire
1 Plug/Spark
07-up 31656-07 0.3 - 0.7 (A-C or A-D) 4 Pin 3,000 - 4,800* Single-Fire
1 Plug/Spark
Sport Model
98-03 31646-99 0.4 - 0.6 (A-B or B-C) 3 Pin 11,700 - 12,700 (Twr1-Twr4 or Twr2-Twr3) Quad Single-Fire
2 Plugs/Cyl/Spark

* The resistance specification in the manual is for one coil only, measured from PinB to either
. . tower on 04-later models. The tower-to-tower measurement would, therefore, be twice that
. . amount since it represents both coils in series. The doubled value is shown above.
From the manual, 04-06 model is listed as 5500-7500 ohms (for one secondary coil) 3)
From the manual, 07-up model is listed as 1500-2400 ohms (for one secondary coil) 4) 5) 6)


See this thread regarding Knock Sensing in 2014+ models
- http://xlforum.net/forums/showthread.php?threadid=2040499


=== Does Ignition Coil Polarity Matter? ===

Up to 2003, the short answer is NO. In fact, the way the dual-fire coils are wound, one plug fires tip to base and the other fires base to tip.7) Most modern coils provide levels of high-voltage (typically, 30,000 volts or more) that exceed any normally required level for standard spark plug gaps.

2004-later (or 98-03 1200S): On connectorized, single-fire coils, be sure any modified wiring matches the connections and polarity specified in the schematics.

See this excellent __XLForum Thread__, especially Post#20 by Fe Head.

Ignition Coil Design

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Coil part numbers have changed several times over the years. The primary resistance values below are typical, but check your FSM for the exact values for your year and model. For aftermarket products, check the primary resistance value with the manufacturer’s data.

How-it-works by Steelworker: An ignition coil is a pulse-type transformer, consisting of a low voltage primary winding (the input) and a high voltage secondary (output) winding, wrapped around a laminated iron core. The primary circuit is completed by the points or electronic ignition module closing the primary circuit to ground. The flow of current in the primary windings induces a strong magnetic field in the laminated iron core. When the primary circuit is broken (by the ground being removed), the strong magnetic field in the core collapses suddenly, which induces a high voltage electrical discharge out of the secondary circuit, thereby, producing a spark strong enough to bridge the electrode gap of each spark plug.

Testing - In General
To test the coil, you will need a multimeter (or DVM) with a low-resistance scale, preferably a scale of 200 ohms or less. Most coils have a primary resistance below 10 ohms and a secondary resistance in the 1,000's of ohms. When testing the primary resistance, you will connect the meter leads to only the primary connectors. When testing the secondary resistance, you will connect the meter leads, typically, to the coil output towers for the spark plug wires.

If the resistance measurements are lower than specified, that winding has partially shorted, bypassing part of the coil. If the resistance is higher, then corrosion or failing internal connections may be adding to the resistance. If the resistance is infinite, the winding is an open circuit. Failing coils cannot be repaired and need to be replaced with compatible products.

Sometimes coil failure is heat related. In that case, simply idling the bike and heating the coil with a hair dryer may cause the coil malfunction to occur and the spark to stop or become intermittent or erratic.

Two different type coils:
There are two basic ignition systems and HD used different coils for each. The dual-fire ignition systems (thru 2003) use a double-coil built into one housing and both coils are always fired together - One output for the front cylinder and one output for the rear. Both coil outputs fire together when the front cylinder needs a spark and both coil outputs fire together when the rear cylinder needs a spark.

Later (2004+), the single-fire ignition system became standard. It uses a double-coil also built into one housing, BUT, each coil fires separately. One coil is charged and fired when the front cylinder requires a spark and the other coil is charged and fired when the rear cylinder requires a spark. Each coil is SINGLY fired when it's cylinder needs a spark.

8)

Ignition Coil Testing

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Dual-Fire Coil Testing (1986-2003)(Except Sport Model - See Below)
The Dual-Fire Coil has only two primary screw terminals (sometimes labeled, + & -) with dual output towers to the spark plugs. 1986-2003 Evos use a coil rated, nominally, at 3.0 ohms (HD P/N 31614-83A). It has primary terminal studs and the primary wires are nutted onto the coil.

The primary resistance is measured across the two input terminals at 2.5 to 3.1 ohms. Secondary (high voltage) winding resistance is tested from coil tower to coil tower. While the actual specs do vary, typically, the range is 10,000 to 12,500 ohms. Check the FSM for the exact primary and secondary coil resistance for your model year.

(Note that Ironheads with points typically use a dual-fire coil with a nominal primary resistance of 5.0 ohms.)

Quad Single-Fire (Quad) Coil Testing (Sportster Sport 1998-2003)
The Sport model is unique - It has two spark plugs in each head. This means the coil must fire two pairs of spark plugs. To do this, the Sport model coil (HD P/N 31646-99) has four internal coils in one housing. They are wired so both front cylinder spark plugs are fired together by two of the coils and then the rear cylinder set of plugs are fired by the other set of coils.

The coil output towers exit at right angles to the Sportster frame. The Front (Left & Right) towers fire the two plugs in the front head. The Rear (Left & Right) towers fire the two plugs in the rear head. The coil primary windings are connected using a 3-pin connector located on the coil just below the upper frame.

The coil has three connectorized primary terminals referenced as pin A(Front), B(V+) and C(Rear). Pin A & C connect the appropriate firing signals and primary terminal pin B(V+) is common to all internal coils. Primary resistance from pin B(V+) to pin A(Front) is 0.4 to 0.6 ohms and likewise the same for pin B(V+) to pin C(Rear). The secondary resistance measurement is taken between both front coil towers (L&R) and then again between both rear coil towers (L&R). The measurement for each is 11,700 to 12,700 ohms.

Single-Fire Coil Testing
The Single-Fire Coil has a separate firing signal input for the Front & Rear plugs.

2004-2006 models - The coil (HD P/N 31655-99) has three connectorized primary terminals referenced as pin A(Rear), B(V+) and C(Front). These same pins are also referenced as 1, 2 & 3, respectively. Pin A & C connect the appropriate firing signals and primary terminal pin B(V+) is common to both internal coils. Primary resistance from pin B(V+) to pin A(Rear) is 0.5 to 0.7 ohms and likewise the same for pin B(V+) to pin C(Front).

You can test the secondary resistance of each individual coil by placing one meter lead on the B(V+) input terminal and then placing the other meter lead on one of the output towers - Taking the reading this way should produce a resistance reading within the range specified in the manual, 5500-7500 ohms. If you test the secondary resistance between both towers (one lead in each tower) you should obtain a reading equal to the sum of the two previous readings - or 2x the spec - Here, that would be a reading between 11,000 & 15,000 ohms.

2007-2013 models - With the introduction of EFI, the single-fire coil (HD P/N 31656-07) has four (4) connector pins in the connectorized primary connector. Looking into the connector on the coil (when the towers are pointing down), the pins (left-to-right) are defined as A(Power), B(Power), C(Rear) & D(Front). Both PinA & PinB are supplied power together by the connecting cable. The C(Rear) & D(Front) pins are the trigger signals, which are grounded by the Engine Control Module (ECM) to charge the coil and released from ground to fire the coil.

Measuring primary coil resistance from pin A to pin D should read 0.3 to 0.7 ohm. Likewise, from pin A to pin C should measure 0.3 to 0.7 ohm.

Maybe» Although PinB is supplied power, it is believed that PinB is connected between the two secondary coils, allowing for the future implementation of ION Sense, the ability to detect combustion when the spark plug fires.

You can test the secondary resistance of each individual coil by placing one meter lead on the PinB terminal and then placing the other meter lead on one of the output towers - Taking the reading this way should produce a resistance reading within the range specified in the manual, 1500-2400 ohms. If you test the secondary resistance between both towers (one lead in each tower) you should obtain a reading equal to the sum of the two previous readings - or 2x the spec - Here, that would be a reading between 3,000 & 4,800 ohms.

When the keyswitch is turned ON (with RUN/Stop in RUN), the ECM causes the ignition power to be on for 2-3 seconds to prime the pressure in the fuel system. Then, the ECM turns off the System Relay and waits for further action by the rider. The System Relay will be activated for ignition power (to the fuel pump, coil & injectors) when the ECM sees CKP pulses (as when the starter is running). If the engine is not running or being cranked (no CKP pulses), the ECM will de-energize the system relay within a few seconds.

2014-later models - The operation for these years is the same as above, except for PinB. In 2014, with the implementation of the CANbus, PinB began to be used for ION Sense, with a separate wire back to the ECM (Pin9). ION Sense allows the ECM to sense combustion when the spark plug fires.


Manually Trigger Coils For Testing Spark

Photo by IXL2Relax of the XLForum 1986-1990 The Ignition Control Module (ICM) is located rearward of the battery behind the triangular cover. The ICM is directly wired to the main harness or it's related components. THERE IS NO CONNECTOR TO USE FOR TESTING. You will need to test at the coil.

On the coil, the BLUE Wire is the trigger wire from the Ignition Control Module & the PINK Wire goes to the Tachometer. The WHITE Wire(s) are power from the Run/Stop Switch.

Remove the BLUE & PINK Wires from the coil - There should now be no wires on that electrical post of the coil. Leave the WHITE wire(s) connected to the other electrical post.

Connect an appropriate length wire to a solid ground point on the frame, long enough to reach the coil. Remove your spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark. You can always use an extra hand clamp.

Turn the keyswitch fully on - Flip the Run/Stop switch to RUN.

Briefly ground the coil by touching your ground wire to the coil electrical post where the BLUE & PINK Wires were previously connected. This will charge the coil and it should fire a spark on both plugs when you remove the wire from the coil.

This will test the coil, spark plug wires & spark plugs to verify a spark is able to be produced. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.

1991-1993 The Ignition Control Module (ICM) is located rearward of the battery behind the triangular cover. It connects to the main harness at Connector 10A/B - a seven-pin connector located behind the battery near the circuit breakers.

Remove connector 10A from 10B - On the pin side (10A), which goes to the main harness, Pin#4 (BLACK Wire) is connected to the main ground while Pin#1 (PINK Wire) provides the trigger for the coil.

Remove your spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark. Turn the keyswitch fully on - Flip the Run/Stop switch to RUN.

NOTE » VERIFY YOUR CONNECTIONS BY COLOR - TAKE CARE NOT TO SHORT ANY OTHER PINS

Use a short piece of wire to briefly short Pin#4 (BLACK) to Pin#1 (PINK) on Cable Connector 10A - By briefly shorting these pins, you will charge the coil and it should fire a spark on both plugs when you remove the wire from those pins.

This not only tests the coils, but all the wiring from the 10A/B connector to the Spark Plugs. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.

1994-1997 The Ignition Control Module (ICM) is located rearward of the battery behind the triangular cover. It connects to the main harness at Connector 10A/B - an eight-pin connector located behind the battery near the circuit breakers.

Remove connector 10A from 10B - On the pin side (10A), which goes to the main harness, Pin#7 (BLACK Wire) is connected to the main ground while Pin#4 (PINK Wire) provides the trigger for the coil.

Remove your spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark. Turn the keyswitch fully on - Flip the Run/Stop switch to RUN.

NOTE » VERIFY YOUR CONNECTIONS BY COLOR - TAKE CARE NOT TO SHORT ANY OTHER PINS

Use a short piece of wire to briefly short Pin#7 (BLACK) to Pin#4 (PINK) on Cable Connector 10A - By briefly shorting these pins, you will charge the coil and it should fire a spark on both plugs when you remove the wire from those pins.

This not only tests the coils, but all the wiring from the 10A/B connector to the Spark Plugs. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.

1998-2003 ALL Except Sport Model
The Ignition Control Module (ICM) is located behind the small timing cover on the Cam Cover. It connects to the main harness at Connector 10A/B - a six-pin connector located under the engine.

Remove connector 10A from 10B - On the socket side (10B), which goes to the main harness, Pin#6 (BLACK Wire) is connected to the main ground while Pin#4 (PINK Wire) provides the trigger for the coil. (Some early versions may have the PINK Wire on Pin#5)

Now take a short piece of wire (paper clip?) and ground one end by inserting it into Pin#6. Remove your spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark.

Turn the keyswitch fully on - Flip the Run/Stop switch to RUN.

Now, very briefly, touch the ground wire to socket Pin#4 of Cable Connector 10B - By briefly touching that pin, you will charge the coil and it should fire a spark on both plugs when you remove the wire from Pin#4.

This not only tests the coils, but all the wiring from the 10A/B connector to the Spark Plugs. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.

1998-2003 (Sport Model only)
The Ignition Control Module (ICM) is located under the seat. It connects to the main harness with two 12-pin connectors - one Gray Connector (11A/B) and one Black Connector (10A/B) - We want to disconnect both, but will only be working with the 10B socket connector.

Remove connectors 11B and 10B from the ICM - On the socket side of 10B (the Black connector), which goes to the main harness, Pin#2 (BLACK Wire) is connected to the main ground while Pin#6 (BLUE/Orange Wire - Front) and Pin#7 (YELLOW/Blue Wire - Rear) provide the triggers for the dual-coil.

Now take a short piece of wire (paper clip?) and ground one end by inserting it into Pin#2.

Remove your front cylinder spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark.
-or-
Remove your rear cylinder spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark.

Turn the keyswitch fully on - Flip the Run/Stop switch to RUN.

Very briefly, touch the ground wire to Pin#6 of Cable Connector 10B (the connector on the cable, not on the ICM itself) - By briefly touching that pin, you will charge the coil for the FRONT plugs and it should fire the front cylinder spark plugs when you remove the wire from Pin#6.
-or-
Very briefly, touch the ground wire to Pin#7 of Cable Connector 10B (the connector on the cable, not on the ICM itself) - By briefly touching that pin, you will charge the coil for the FRONT plugs and it should fire the front cylinder spark plugs when you remove the wire from Pin#7.

This not only tests the coils, but all the wiring from ICM to the Spark Plugs. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.


On 2004-later models, the ICM will not fire with both spark plugs removed. At least one spark plug
must be installed to create engine compression. For simplicity, for all 2004-later tests, you can
use a spare, known good, spark plug that is grounded to the engine fins. Connect the spark plug
wire under test to the spare spark plug rather than removing the original in-cylinder spark plug. 9)

2004-2006 10)
Find the Ignition Control Module (ICM) under the seat - Remove the connector from the ICM (12 pin connector known as 10A/B). On that connector, Pin#5 (BLACK Wire) is connected to the main ground while Pin#6 (BLUE/Orange Wire - Front) and Pin#7 (YELLOW/Blue Wire - Rear) provide the triggers for the dual-coil.

Now take a short piece of wire (paper clip?) to use as a jumper and ground one end by inserting it into Pin#5. Connect a spare spark plug to the front spark plug wire and ground the plug to a solid ground point (like the fins) where you can observe the elements for a spark.

Turn the keyswitch fully on - Flip the Run/Stop switch to RUN.

Now, very briefly, touch the grounded jumper wire to Pin#6 of Cable Connector 10B (the connector on the cable, not on the ICM itself) - By briefly touching that pin, you will charge the coil for the FRONT sparkplug and it should fire a spark when you remove the jumper wire from Pin#6.

Remove the front spark plug cable. With the spare spark plug grounded to the fins, connect your rear spark plug cable to the spare plug.

Now briefly touch the grounded jumper wire to Pin#7 of Cable Connector 10B - This will energize the coil for the REAR plug and when the jumper wire is removed that coil should fire the rear spark plug.

This not only tests the coils, but all the wiring from ICM to the Spark Plugs. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.

2007-2013 With the implementation of the Eletronic Fuel Injection Ignition System, there is now a System Relay. The Engine Control Module (ECM) is located under the seat.

Remove the connector from the ECM (36 pin connector known as 78A/B). On the socket connector (78B), Pin#10 (BLACK Wire) is connected to the main ground while Pin#29 (BLUE/Orange Wire - Front) and Pin#11 (YELLOW/Blue Wire - Rear) provide the triggers for the dual-coil. Pin#2 provides the grounding activation for the System Relay.

Take a short piece of wire (paper clip?) and ground one end by inserting it into Pin#10. Then, place the other end into Pin#2 to create the missing activation signal for the System Relay. Remove your spark plugs and ground them to a solid ground point (like the fins) where you can observe the elements for a spark.

Place another short piece of wire (paper clip?) into Pin#11 and short it to Pin#10. Turn the Run/Stop switch to OFF/STOP - Turn the keyswitch fully on. Now, briefly, flip the Run/Stop switch to RUN and then back to OFF/STOP. By briefly activating the RUN switch, you will charge the coil for the REAR cylinder and it should fire the rear spark plug when you switch back to OFF/STOP. Turn the keyswith to OFF.

Remove the wire from Pin#11 and place it into Pin#29 and short it to Pin#10. Turn the Run/Stop switch to OFF/STOP - Turn the keyswitch fully on. Now, briefly, flip the Run/Stop switch to RUN and then back to OFF/STOP. By briefly activating the RUN switch, you will charge the coil for the FRONT cylinder and it should fire the front spark plug when you switch back to OFF/STOP. Turn the keyswith to OFF.

This not only tests the coils, but all the wiring from ICM to the Spark Plugs. Power down and put everything back where it belongs.

If this test fails to produce a spark at each spark plug, and the spark plug wires and spark plugs are functional, then the coil itself is suspect. A (temporary) replacement coil should be utilized and the test performed again.

2014-later Because the ECM/BCM is so fully integrated with all the operating components, it controls power to the coil. It is no longer a simple matter to test from the ECM to the coil.


Manually Trigger The Ignition Control Module For Testing Spark

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This information ONLY applies to 1986-1997 All Models & 1998-2003 'S' Models
These models use a Cam Sensor Plate that is separate from the Ignition Control Module.

This information does not apply to the non-'S' models of 1998-2003 which use an integrated Ignition Control Module on the Cam Sensor Plate in the nosecone. It also does not apply to 2004-later models which use a Crankshaft Position Sensor (CKP) instead of a Cam Sensor.

The Cam Sensor connects thru the main wire harness to the Ignition Control Module. It uses a 3-pin connector, known as 14A/B. It is located under the engine (left side near the kick stand). The 14A (plug) comes from the Cam Sensor Unit - the 14B (socket) is on the main harness and goes to the ICM.

11)12)
On Connector 14B (3-pins), the wires function as follows:

  • Pin(A) Red/White - 12v Power from ICM to Cam Sensor - 5v power for 1998-2003 'S' Models 13)
  • Pin(B) Green/White - Rotor Signal from Cam Sensor to ICM
  • Pin(C) Black/White - Ground from ICM to Cam Sensor

(Note: the 1998-2003 Sport model uses the same Cam Sensor & Connector as the 1994-1997 models. The slotted rotor cup is different on the Sport models, having additional slots to allow for the single-fire ignition. Note also, with the new ICM module and the addition of a MAP Sensor, the power to the CMP Sensor is 5v (also to the MAP Sensor) for the 1998-2003 'S' models.)

Testing the ability of the ICM to sense the Cam Rotor & fire the Coil

  • With the rest of the wiring in tact, disconnect the Connector 14A/B
  • Turn the Keyswitch to ON & place the RUN/STOP switch in the RUN position
  • Using harness Connector 14B (which goes to the ICM), briefly short Pin(B) to Pin(C) using a paper clip in the sockets
  • Note: The first four signals are ignored so do this 6-10 times
  • After the first four times, when the short is broken, the ICM should fire the coil
  • (CAUTION - Never short (A) to either other pin or to ground)

If this test succeeds, yet no spark is produced when cranking the engine with the Cam Sensor connected, then the Cam Sensor is suspect and may need replacing. (Note: The Cam Sensors fail very rarely. Double check your testing.)

If this test fails to produce a spark at each spark plug, and the spark plugs, plug wires and coil are functional, then the Ignition Control Module itself is suspect. (Note: The Ignition Control Module rarely fails.) Use a (temporary) replacement ICM and run the tests again.

Spark Plugs

Year Model Use/Type HD Plug Alt. Plug Brand/Number Ignition Type Spark Gap
1986-2016 HD 6R12 (resistor type) Autolite 4164
Bosch YR6LDE
Champion RA8HC
NGK DCPR7E
Screamin Eagle EX12S
Electronic Ign. 0.038-0.043“


12mmX1.25mm Threads - 12-18 ftlbs torque
Wrench = 5/8” or 16mm


VOES - Vacuum-Operated Electric Switch

  • The VOES was first installed on Sportsters in 1983 (and used on most models thru 2003). The unit senses intake manifold vacuum at the carburetor and requests that the Ignition Control Module (ICM) switches between one of two different spark advance curves. The switch is closed at high vacuum operation, utilizing a more advanced spark curve and it is open at low vacuum operation, utilizing a less advanced (retarded) spark curve to minimize engine knock and still maintain performance. The VOES is installed above the intake manifold. 14)
  • VOES: Its Operation & Adjustment.
    • There are many discussions on the XLForum and elsewhere regarding the VOES unit. While there are many helpful posts among those discussions, there is still much confusion due to posts that are inaccurate. I hope to clarify the VOES operation with this post and a reference diagram.
    • The VOES unit was used on the Sportster from about 1983 (Ironhead) to 2003 (Evos). But, note that the 1998 to 2003 Sport models did not have a VOES but rather pioneered the use of a MAP sensor like that used on 2004 and later model Sportsters. Those models have Engine Control Modules which can micro-manage the ignition advance based on multiple conditions.

Here's what the VOES looks like with a quick reference chart of it's operation: 15)

  • .
    • What it does and how.
      • The VOES works in conjuction with the Ignition Control Module (ICM) to control ignition timing. The ICM has two timing curves - one is for idling or cruising and the other is for WOT and/or for powering up for high loads (like steep hills). The VOES switches the ICM between these two pre-programmed advance curves based on manifold vacuum.
      • The built-in curves of the ICM vary timing based on the engine RPM. The VOES allows a choice between timing curves based on engine load because the load will vary even though the RPMs are the same (different gears, different terrain, etc.)
      • The VOES has two connections and one adjusting screw. The VOES is connected to the carb (manifold side) through a vacuum hose and monitors the manifold vacuum level. It is also connected to the ICM. It has two black wires from the internal switch. From the inline connector, there is a (purple or purple/white) single wire sent to the ICM and a second wire sent to ground. The VOES switching point is set by a concealed screw. This causes the ICM to switch between the two advance curves based on a set point level of manifold vacuum.
      • The adjusting screw is inside a sealed opening on the VOES. You must dig out the silicone sealing compound in order to make any adjustments. Remember - When testing your adjustments, you must also seal that opening with your thumb (or other air-tight sealing compound or tape) in order to prevent air leakage through the screw adjuster cavity.
      • The only function of the VOES is to switch between the two advance curves that are programed into the ICM. Different ignition modules have different curves. Those curves have anywhere from 5 to 18 degrees difference in the advance settings between them. But that's another discussion.
      • The manifold vacuum directly controls the VOES, but the throttle position (and/or it's aggressive changes) indirectly alters the VOES (thru changes in the manifold vacuum) by altering the carburetor throttle plate.
      • When the engine is running at idle, when lightly accelerating or when using a steady cruise throttle, manifold vacuum is high (the throttle plate is mostly closed) and the VOES switch is ON, causing the ICM to use the MORE ADVANCED CURVE.
      • When the engine is not running or when the throttle is quickly opened to accelerate or to satisfy a heavy load (steep hill, extra weight, etc.), the manifold vacuum drops and the VOES switch goes OFF, causing the ICM to use the RETARDED (OR LESS ADVANCED) CURVE. If you let off the throttle (when you reach your speed or top the hill), the manifold vacuum rises again. The VOES senses this and will again switch ON, causing the ICM to return to the MORE ADVANCED CURVE as the load on the engine becomes lighter.
      • Running without a VOES causes the ICM to run on ONLY the less-advanced power curve. The ICM cannot switch curves. Unless you have a highly modified engine, this will hamper smooth engine operation on light acceleration and reduce fuel savings during cruising.
      • Also note, if the VOES switching point is set too low, it will remain on the more advanced curve too long under mid-load acceleration and pinging will occur. This is the reason that engines with upgraded performance should have their VOES switch point increased (switch at a higher vacuum level) to better match the capabilities of the engine.
  • Testing the VOES Operation - HD Bulletins
    • Method #1 16)
      • After the engine timing has been properly checked / adjusted, perform the following check:
      • With the engine idling, remove the vacuum hose from the carburetor and momentarily plug the carburetor fitting. Timing will retard and engine speed should decrease. Reinstall the vacuum hose to the carburetor. The timing mark should reappear and engine speed should increase to the preset speed. If the engine speed does not decrease and increase as described, check the VOES wiring connection to the computer module and ground wire. VOES must be replaced if malfunctioning.
    • Method #2 17)
      • You will need a vacuum pump (with gauge) to create the desired vacuum level and an ohm meter.
      • Remove the air cleaner, disconnect the switch wire from the computer module connector under the fuel tank and remove the switch vacuum hose from the carburetor. The rear of fuel tank may have to be raised to disconnect the switch lead connector from the computer module connector.
      • Attach the ohmmeter leads to the switch wire and to ground. Attach the vacuum pump hose to the switch vacuum hose.
      • The ohmmeter should indicate the switch closed with 3.5 to 4.5 in. of mercury vacuum applied. If more or less vacuum is required to close the switch, replace it.
  • Testing the VOES Switch Point
    • To test your VOES unit (or adjust it to a specific switching point), you will need a vacuum pump (with gauge) to create the desired vacuum level and an ohm meter to test whether the VOES has switched on (causing a short between it's wires).
    • To work on the VOES, remove the vacuum hose from the vacuum line tee where it branches to the vacuum-operated petcock. If you don't have a vacuum-operated petcock, and have no tee, you need to remove the vacuum hose from the carb. Then remove the VOES from it's mount under the fuel tank and disconnect the wires.
    • Connect your vacuum pump to the hose and connect your meter (set on ohms) to both wires. As you slowly pump up the vacuum, there will come a point where the meter will switch from infinity to zero ohms. This is the switch point. Write down the indicated vacuum (inches of mercury). Release the vacuum and do the test again, just to be sure you get a consistant reading.
    • If the reading is right (according to the manual or chart above) for your bike, you can leave it as it is. If your bike is stock or only upgraded to Stage 1 level, you probably do not need to alter the factory VOES setting. But if you've gone farther with your mods, you might have one of those engine builds where the combination of ignition curves, cams, heads, etc., leaves you with some pinging near the VOES switch point. If you want to make your VOES switch at a different point, read on.
  • Adjusting the VOES Switch Point
    • Dig out the original sealing compound which fills the opening where the adjusting screw is located. Do this carefully so as not to damage the internal screw or diaphragm or the VOES housing. Remember - When testing your adjustments, you must also seal that opening with your thumb (or other air-tight sealing compound or tape) in order to prevent air leakage through the screw adjuster which will skew your readings.
    • To adjust the VOES to switch at a higher vacuum, turn the adjuster screw 1/4 turn clockwise. Now repeat the test from above to see where (in inches of mercury) the new switch point occurs. If you want it to switch at a lower vacuum level, turn the adjuster screw 1/4 turn counter-clockwise. Keep adjusting the screw (carefully) to raise or lower the switch point. You should not go more than 1 or 2 full turns from the initial setting. If you turn the screw too far clockwise, you'll damage the internal diaphragm and need to replace the unit.
    • When you are done making adjustments, you'll need to plug up that hole. But do this very carefully - Be sure you DON'T GET ANY SILICONE DOWN NEAR THE SCREW. Use only enough to plug the end of the opening and then set it aside to fully cure (probably 24 hours) before reinstalling on your bike.
  • Variety of VOES
    • From the book '101 HD Evo Performance Projects by Kip Woodring & Kenna Love', HD installed VOES on different models with their adjustment set for different switching points. These vacuum settings are measured in inches of mercury. The VOES are color-coded at the sealed end to indicate what setting was used on a particular unit. (I have seen very few with colors other than the natural greyish white - so perhaps HD did not keep up this practice)
    • No Color - - - 7.0 in. Mercury – Early Evo FLT (1984)
    • RED Color- - - 5.5 in. Mercury – Late Evo FLT
    • WHITE Color - 4.0 in. Mercury – Evo FXR & XL
    • BLUE Color - - 4.0 in. Mercury – Evo Softail
    • All of these VOES should be adjustable to other settings. As far as I know, there is no difference in the various VOES units themselves other than their predefined factory settings.
    • The 2003 Sportster Service Manual says the correct Sportster VOES has a Blue paint mark at the vacuum hose fitting 18)

* READER BEWARE!!! …NOT EVERYTHING YOU READ ONLINE IS VALID INFORMATION…

  • There's a lot of MIS-information about the VOES & its operation!
  • There are many threads with references to the VOES and how it works, or how it should be adjusted, or what effect it will have. I've only posted above some of the information that is valid. But there is so much confusion surrounding the VOES that you must read all statements carefully to keep from being misled.
  • There is a Sticky Thread in the 'Engine Conversion' section titled 'VOES ADJUSTMENT' - Be careful of the information presented there regarding the VOES. “This is the most confusing conglomeration of instructions I have ever read. There is some bad info, some completely wrong info, and some very dangerous info.” (A comment from Post# 113)
  • That thread has some information about connecting an LED light to the VOES-to-Ignition wire to see the VOES switching modes while riding. If you try this, just be careful to read the information thoroughly and understand what you're doing before proceeding. This is the link to that thread: http://xlforum.net/forums/showthread.php?t=57534

19)

IGNITION TIMING - All Models Thru 2003

  • Ignition timing is when the spark takes place - specifically as the piston is traveling UP on the COMPRESSION stroke (compressing the gasses so that you get the most out of the explosion/ignition). 20)
  • Top Dead Center is when the piston is at the VERY top of its travel, in the center of it's dwell area, and is usually referenced to mean on TDC of the COMPRESSION stroke (with the valves closed and the mixture compressed), though the piston will also be at TDC on the Exhaust stroke when the flywheel turns one complete rotation in either direction from TDC of compression. 21) So, the piston will be at TDC twice per 1 full revolution of the cams. Timing is measured (and set) from TDC on the compression stroke. See more on Finding TDC on Compression Stroke in the Sportsterpedia.
  • Spark ADVANCE - is how soon, BEFORE the piston reaches top dead center (or how late - AFTER top dead center) that the spark plug fires to start burning the mixture. The faster the motor is turning, the sooner you need to start the ignition (more advanced it needs to be) so that power of the expanding gasses starts pushing on that piston as soon as it starts moving downward and pushes as long as will be beneficial. 22)
    • Ignite it too soon, and the gasses start pushing down as the piston is still coming up (spark knock, pinging etc). 23)
    • Ignite it too late, and you loose a lot of the power of the gases, since the piston will reach bottom before the gasses finish expanding. 24)
0°=TDC 20°BTDC Adv 40°BTDC Adv Timing Hole
Year Timing Mark Timing Mark Timing Mark Lt/Rt Notes
1986-90 Vertical Line Single Dot None Left Side Approx. 1000rpm=20°Adv - Using Timing Light - Look for Single Dot - 4sp Trans
1991-95 Vertical Line Single Dot None Right Side Approx. 1000rpm=20°Adv - Using Timing Light - Look for Single Dot - 5sp Trans
1996-99 Vertical Line Double Dots Some-SingleDot Right Side Approx. 1000rpm=20°Adv - Using Timing Light - Look for Double Dots
2000-03 Vertical Line Double Dots Some-SingleDot Right Side Approx. 1000rpm=20°Adv - Using Timing Light - Look for Double Dots - Press Fit Flywheel
The Timing Hole Plug (HD P/N 720) can be removed with a 3/8“ Allen Hex Key - It has 5/8-18 threads
2004-later No Timing Hole or Timing Marks on Flywheel - Base Timing is set in programmable Engine Control Module using CKP Sensor at Flywheel Teeth

All models between 1986-1997 used a movable Cam Sensor Plate with the ignition module located elsewhere. The 1200S model continued to use this configuration from 1998-2003. But in 1998, except for the 1200S models, the ignition module was incorporated onto the Cam Sensor Plate. The combined ICM/Cam Sensor Plate (aka Nosecone Ignition) provided for dynamic timing (engine running - moving plate) in the same way as before, plus it also allowed Static Timing (engine not running).

The timing hole (in the engine case) was located from 1986-1990 on the left side of the engine & from 1991-2003 on the right side of the engine. In 2004, with the introduction of the CKP Sensor for timing, the nosecone cavity was empty and timing adjustments required programming the new Engine Control Module with a computer. There is no timing hole on the 2004-later models.

The movable plate (either separate or integrated version) is used to set the base timing for the ICM advance curves. Since there is no marked TDC or advance timing position marked on the plate itself, the timing plate will be set while viewing the flywheel advance timing marks on a running engine. Correct timing is always set on the compression stroke of the front cylinder(both valves closed).

The timing marks on the flywheel can be seen thru the timing hole, which is situated on the left or right side of the engine, on the crankcase just below the cylinders. The timing hole plug can be removed with a 3/8” Allen Hex Key. Removing the Timing Hole Plug allows you to find the timing marks by peering into the hole. Use the clear timing plug when doing a dynamic setting of the timimg with a timing light flashing into the clear plug to highlight the marks on the flywheel.

The Nosecone Ignition unit (98-03 not-S) can be statically timed (without the engine running) using the built-in LED. The procedure is to manually rotate the engine (bike on lift, 5th gear, rotate rear tire to rotate engine) to position the engine to TDC (front cylinder compression stroke) using the timing hole to look for & center the vertical line. Then, turn the ICM/Cam Sensor Plate slightly clockwise & counterclockwise to find the exact spot where the light switches between on & off - Lock down the plate.25)

To set the timing dynamically, first, remove the timing plug & install the clear timing hole viewer plug (It MUST NOT touch the flywheel). Connect the clamp of an inductive pickup timing light (powered by the battery) to the front spark plug wire. This will allow you to 'shoot the light' into/thru the clear viewer plug. Then start the engine, set the idle at 1000rpms & shoot the light into the timing hole. Move the timing plate so that the 20° advance timing mark shows up in the center of the timing hole.

Moving the Cam Sensor Plate Clockwise (CW) will increase the Advance Before TDC. Moving the plate Counterclockwise (CCW) will retard (or reduce) the Advance Before TDC. Note that each timing mark on the plate (long-to-short) is equal to changing the ignition timing by 5°. Move the plate VERY LITTLE to make adjustments.

The Cam Sensor Plate can be rotated slightly to accomodate getting the timing mark in the center of the timing hole. You can also move the plate to change the base timing (thus moving the whole curve sets up or down in rpm range) by setting the 1000rpm timing to a few degrees more or less than the specified (20° BTDC) advance timing mark.

Adding more advance will increase the likelihood of pinging when the engine is hot and/or under heavy acceleration. It is not recommended to move the timing (from 20°BTDC) more than an absolute total of 10° either way. That's only two tick marks!

More Information Here: http://xlforum.net/forums/showthread.php?threadid=2008019

For Front Cylinder Compression Stroke: 26)




1)
1959-1985 Clymer Sportster Repair Manual pg 229
2)
Article by steelworker of the XLFORUM
7)
2003 Sportster Service Manual 99484-03 p.7-24
8)
Updated by IXL2Relax - includes parts from SportsterDoc's post on the XLForum - http://xlforum.net/forums/showthread.php?t=1780092
9)
NOTE from 2004 EDM: Engine will not spark with both spark plugs removed. When checking for spark, use SPARK TESTER (Part No. HD-26792) with both plugs installed.
11) , 12) , 15)
Illustration created by IXL2Relax at the XLForum
13)
IXL2Relax at XLForum.net
14)
1959-1985 Clymer Sportster Repair Manual pg 230
16)
HD Service Bulletin #M-856 dated August 6, 1982
17)
HD Service Bulletin #M-858 dated October 7, 1982
18)
2003 Sportster FSM, 99484-03, page 7-14
19)
Most of the above information comes from an article by IXL2Relax of the XLFORUM.net http://xlforum.net/forums/showthread.php?t=1863153
26)
Images annotated by IXL2Relax at the XLForum
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