EVO: Engine Control

This information 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 is a Hall-effect device mounted onto the Cam Position Sensor Plate. It is used in conjunction with a rotor 'cup' mounted to the end of the camshaft. As the cup rotates, it passes through the Cam Sensor. Slots in the cup walls are 'timed' to the engine, allowing the cam sensor to indicate the position of the cam shaft, and therefore, the position of the crankshaft.

The Cam Sensor connects thru a wire harness to the Ignition Control Module. It uses a 3-Pin triangular Deutsch Connector, known as 14A/B. It is located under the engine (left side near the kick stand). 14A (with pins) comes from the Cam Sensor - 14B (with sockets) goes to the ICM.

On Connector 14B (3-pin Triangular Deutsch) the wires function as follows:

• Pin(A) Red/White - 12v Power from ICM to Cam Sensor
• Pin(B) Green/White - Cam Sensor Signal to ICM (uses Rotor)
• Pin(C) Black/White - Ground to Cam Sensor

(On older models, the wires may be a solid color without a white stripe)

Testing the Cam Sensor

You can test the Cam Sensor by inserting a stick pin or needle in the backside of Pin(B) on connector 14A/B while it is still connected together. Then connect your multimeter RED probe onto the pin/needle placed in Pin(B) and your BLACK meter probe on a solid ground point. Pull the spark plugs (so the engine turns easily but won't start) and turn the keyswitch on. Then use the starter button to bump (rotate) the engine.

When the engine is rotated, the slotted cup rotor (in the 'nosecone') on the end of the camshaft will pass thru the cam sensor creating an alternating output on Pin(B). Since the sensor has a 12v power source, the variation should be from below 2v to above 10v.

The CKP sensor is located in the front left side of the crankcase. The CKP sensor generates an AC signal which is sent to the ECM where it is used to reference engine position (Front TDC) and speed. It functions by taking readings off the 30 teeth on the left side flywheel (32-tooth positions, but two teeth are missing to establish the front TDC reference point).

Troubleshooting ¹⁾
Disconnect the electrical connection for the CKP Sensor.

(A) Check resistance between each lead of the CKP sensor and ground - Each side should be more than 1-megohm of resistance.
(B) Set your meter to Volts-AC (20v) and connect across both leads of the CKP Sensor - Briefly crank the engine - You should read a minimum of 1v-AC on the CKP Sensor leads. Turn off power.
(C) Keep your meter connected to the sensor connector - Set your meter to Ohms - Between the two leads, you should read 600-1200 ohms.

RESULT
If any test fails - remove the CKP sensor from engine, clean any debri from sensor, reinstall properly - Recheck your results - If the unit still fails (especially if no voltage), replace the CKP.

See this helpful __XLForum Thread__.

The Manifold Absolute Pressure sensor was introduced on the 1998 Sport model and fully implimented on all models from 2004-later with EFI ignitions. It provides information to the ICM/ECM to alter the timing of the spark based on the current vacuum conditions in the manifold. By altering the timing, better combustion occurs in varied situations.

(It replaces the older VOES function.)

The TMAP sensor combines the MAP and IAT in a single component.

The VSS is a hall-effect device located on the engine, just above the sprocket cover and near the rear of the starter solenoid. The sensor output is varied by proximity to the teeth on the 5th gear in the transmission.

(1995-2003) (1995 = P/N 74421-95 - 1996-2003 = P/N 74402-95)
The VSS is a 12v-based hall-effect sensor. The 12v power source is supplied by the speedometer on the RED wire, the BLACK wire is ground and the WHITE wire is the pulsing signal sent directly to the speedometer.

Because the external final drive ratio may vary by model (883 vs 1200), the speedometers are different for different models because they must internally account for the difference in final drive ratios.

Troubleshooting - For models from 1998-2003, you should check your speedometer for Diagnostic Codes to see if there is an indication of a faulty sensor reading. If you are experiencing erratic speedometer readings, removing and cleaning the sensor should be done to obtain a clean signal.

The sensor output is a square-wave which varies from 'less than 3v' (when at a tooth) to 'greater than 9v' (at a gap). A multimeter on a low DC scale should be able to observe this output on the WHITE wire of the sensor.

If you are able to observe the above voltages from the sensor, but the speedometer is still erratic or otherwise malfunctioning, be sure to test all the wiring between the sensor and the speedometer. As a last resort, replacement of the speedometer may be in order.

A very informative __XLForum Thread__ regarding the VSS.

(2004-2013) (2004-2012 = P/N 74402-04A - 2013 = P/N 74402-05B)
The VSS is a 5v-based hall-effect sensor. The 5v power source for the sensor (BLACK/RED wire of the twisted pair) comes from the ICM/ECM and the pulsing output from the sensor (BLACK/BLUE wire of the twisted pair) goes to the ICM/ECM for processing. The ground connection (BLACK wire) is part of the main harness.

Internally, the ICM/ECM calculates the appropriate speed information and sends that information to the speedometer and the TSM over the Serial Data Bus. Since the ICM/ECM makes the calculations, the speedometer and TSM do not have to account for any variations.

Troubleshooting - Check your speedometer for Diagnostic Codes to see if there is an indication of a faulty sensor reading.

The sensor output is a square-wave which varies within the 0v to 5v range, depending on the proximity to a tooth. The middle pin of the connector is the output and is, typically, the BLACK/BLUE wire. A multimeter on a low DC scale should be able to observe this output variation.

If you are experiencing erratic speedometer readings, removing and cleaning the sensor should be done to obtain a clean signal.

If you are able to observe the above voltage variations from the sensor, but the speedometer is still erratic or otherwise malfunctioning, be sure to test all the wiring between the sensor and the ICM/ECM as well as the Serial Data Bus connection. As a last resort, replacement of the speedometer may be in order.

(2014-on) (P/N 74402-05B)
The VSS sensor is the same 5v-based hall-effect sensor as 2013. The ECM (Engine Control Module) handles all the processing of the signals and sends data to the speedometer over the new CANbus communications connection.

The Bank Angle Sensor, as an individual component, is used on Sportsters from 1998 to 2003. It is intended to kill the ignition if the bike lean angle exceeded 55 degrees, such as in an accident or tip over. It is attached to the side of the battery box, toward the rear, using a locating pin and one screw. It has a 3-wire connector.

The sensor can be tested while the bike is running, by placing a magnet at the top of the sensor. If the ignition stops, the sensor is working. The sensor is sometimes unreliable, either failing to allow the bike to start or by not shutting down on tipover. Some have chosen to bypass the unit.²⁾

Beginning in 2004, the bank angle function is included inside the Turn Signal Module (TSM/TSSM).

To reset the function after triggering, turn off the keyswitch, set the bike upright, turn the keyswitch on.

The Oil Pressure Switch is located at the Oil Filter mount. It is a pressure-actuated diaphragm-type switch that indicates a lack of oil pressure. The switch grounds the sensor wire when there is insufficient oil pressure to open the switch and causes the oil light to illuminate on the indicator bar or the speedometer.

If the idle speed should fall below 1000rpms, the light may activate as a warning.

The Neutral Indicator Switch is located forward of the main drive gear shaft on the right crankcase half. A pin on the transmission shifter drum contacts the switch plunger to indicate a neutral position of the transmission. The switch grounds the sensor wire causing the neutral indicator lamp to light (on the indicator bar or in the speedometer).

It cannot be removed for replacement without removing the final drive transmission sprocket.