Test the I.C.M. or E.C.M.

The I.C.M. (ignition control module) was used on Sportsters before the year 2007. After 2007, the module became integrated into the E.C.M. (electronic control module). These modules contain internal circuitry found on most computer motherboards. The voltages used on these circuits are very small and hard to test. The easiest way to test a computer module is by verifying its power and ground connections are correct.

To test your module's power and grounds:

1. Find the wiring diagram for your year's Sportster in a service manual, or from your local Harley dealership.
2. Locate the power and ground wires.
3. Measure the power wire's voltage. Set your meter to read DC volts. Place the red probe on the power wire at the ignition module/E.C.M. and the black wire on a good ground; 12 volts should be present with the ignition in the on/run position.
4. Measure the ground wire's voltage. Place the red probe on the ground wire at the ignition module/E.C.M., and the back probe on battery positive; 12 volts should be present with the ignition in the on/run position.
5. To verify the power wire is undamaged, measure the voltage drop on the power wire by placing the red probe near the power wire's connection of the battery and the black probe on the power wire near the ignition module/ E.C.M. If the voltage drop is less than 0.5 volts, the wire is okay.
6. Do the same test for the ground wire. Place the red probe on the ground wire's connection closest to the battery and the black probe on the ground wire at the ignition module. If the voltage drop is less than 0.5 volts, the wire is okay.