REF: Electrical System

Body Control Modules - Aftermarket

Motogadget M-Unit Blue

This unit is designed to replace the power control device on your motocycle. It does not provide engine spark or timing, so you must supply (or keep) that part of the motor control devices (points & mech advance or ignition module & timing sensor, coil, etc). Their main website is

The m-unit operation (and the manual) is updated regularly so it is important to know which version you have to know what functions are programmable. The manuals are not dated, so pay attention to the version & S/N references.

Take note that most input switch connections are expected to activate the signal by grounding the input. This may not be the way the stock switches are configured.

Document Links:
mo.unit blue / basic - v3.0 -

Older links (may no longer be valid):

Revival Cycles' has done a number of YouTube videos (called Tech Talk) and has some documentation as well.

The Ins and Outs of the Motogadget M-Unit Blue (21:13min)

This diagram may or may not be like your setup (may not be helpful):

Using Your Phone to Connect to the m-unit:

Thunder Heart - EA4250D

This section is related to the Electronic Harness Controller available from Thunder Heart Performance Corp. The information gathered here was due to a significant effort by XLForum member, Roane, while trying to implement the EA4250D on his Ironhead Sportster. 1)

The TH EA4250D controller works in conjunction with whatever spark timing system you have, whether points, Ignition Control Module or later Engine Control Module. In any case, the TH unit does not control the spark creation or timing but rather simply controls the power to the coil (and ignition module) in order to allow or prevent the engine from running.

The installation manual can be downloaded at the Thunder Heart website ( It should be consulted carefully in conjunction with the added information below. The manual information is not repeated here.

Here is an overall diagram to detail the connection of various switches, lights, sensors, etc. (click on an image to see a larger version):

Note that the Auxiliary Power Outputs at J1-Pin1 and J5-Pin1 are both keyswitched power.
They are ONLY ON when the Keyswitch is ON.

The following image shows the typical wiring that would be used for the
right-hand HD control - Wire colors are for the TH wire harness:


Note that on most Sportsters, all the way up thru 2013, the wiring configuration is
functionally the same as above (with only some minor wire color variations - or
those noted in the TH Install Manual). The BLUE jumper wire shown in the
diagram between the RUN/STOP Switch and the Starter Button is typically
internal to the RH Switch Housing.

Below is a diagram of the ignition connections, from the handlebar switches to the Starter Motor.
This is intended to explain the operation of the internal Start Relay in relation to the RUN/KILL &
START switches. The shown internal connections are functional representations and do not represent
that these connections are simply jumper-wired as shown. (This configuration was gleaned from the
manual (minimal info) and from continuity testing. It is believed to be accurate, but no guarantee.)


Ultima 18-530

This module looks very much like a re-badged version of the ThunderHeart EA4250D.

CANbus Optional Equipment


The CAN-Switchbox is intended to give you the ability to use alternative switches, speedometer & tachometer on H-D models that use the CANbus. The unit simulates the original functions that were implemented on the Right/Left-Hand Control Modules and also the Speedometer. You are able to use switches and pushbuttons from different supplier.

Can-Switchbox Overview

User Manual (from Ser#500)

User Manual (from Ser#600)

User Manual (from Ser#900)

2) , 3) , 4)
Created by IXL2Relax of the XLForum
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