5/30/2023 0 Comments Evo harley wiring diagrams simpleThe 1200Sport model pioneered the Single-fire Spark system and the Manifold Air Pressure sensor (MAP) for the future Sportster models. The 1998-2003 1200Sport model used an independent Ignition Control Module and the same Sensor Plate as the 1986-1997 models. The same procedures can be used to test the ignition coil for heat failure. Somtimes, these two methods can be used in combination to create & resolve a failure condition, although heat related problems can still be hard to diagnose/resolve. If the ICM has failed due to heat, this test will check if it will begin to produce a spark again after being cooled down. Heat Test - Method #2 - Once you have a running failure from heat, use 'cold spray' to quickly cool down the ICM (in the nosecone). After it's warm, see if the engine fails to start due to the spark missing or intermittent. ![]() With a cold engine, use a hair dryer to blow heat on the ICM (in the nosecone) before attempting to start it. Heat Test - Method #1 - If the bike usually fires when cold but dies when warm/hot, test the ICM with the engine cold. Method One makes the ICM fail when the engine is cold, while Method Two tries to make the ICM begin functioning again after it has failed due to heat. There are two methods of testing the ICM relative to heat failures. Various other, less common, symptoms may occur from a failing nosecone ignition module (misfiring, backfiring, etc.). This can be extremely frustrating as the bike will randomly stop while riding. In this case, once the engine cools down, the ICM may allow the engine to fire up again. The ICM may also fail due to heat even though it fired up cold. Some riders report that flicking the RUN/STOP switch (which sends power to the ICM and the coil) several times will sometimes allow the bike to fire up. The bike may refuse to fire even though the starter will turn the engine over. ![]() The ICM may fail with a number of different symptons, with some randomness. The only current choice for replacement is aftermarket versions (such as the Ultima brand discussed HERE or the equivalent from another brand). The MoCo stopped providing replacement units as soon as they were allowed. These OEM modules had a high failure rate, apparently due to the high heat in their mounting location. A Bank Angle Sensor (BAS) was also connected to the ICM as an interlock to stop the engine & prevent restarting the engine if the bike was on it's side. The 1998-2003 Non-Sport model used an integrated ICM on the Sensor Plate (which was still located in the 'nosecone' behind the round cover) and was still a Dual-Fire Spark System. The spark advance (curve) starting point can be altered by physically rotating the sensor plate which is located in the 'nosecone' behind the round cover. 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. ![]() This produces a spark on both plugs at the same time, regardless of which cylinder is currently under compression. The dual-encapsulated coil is fired by only one coil trigger wire from the ICM. The ICM for these years uses a Dual-Fire Spark system. Some of the variation in the P/N was to designate different terminations of the module cable (such as direct wire or 7-pin plug or 8-pin plug). 1) These advance curves were modified over the years as indicated by the Curve Letter printed on the modules (such as G, J, K, Q). A Vacuum-Operated Electric Switch (VOES) is used (since 1983) to switch between 2 different spark advance curves built into the ICM. The ICM computes ignition timing advance and coil dwell. The inductive pickup generates Top Dead Center (TDC of piston) pulses that are sent to the solid state Ignition Control Module (ICM). The components for the ignition system includes a timing rotor (timing cup), sensor plate with an inductive pickup, ignition control module, ignition coil and spark plugs.
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