Table of Contents
What causes ICM to fail?
The common cause of one driver/transistor failing is a shorted ignition coil primary winding. This is a winding of wire within the ignition coil where each loop is separated by a very thin plastic coating.
How do you check the ignition module on a GM HEI distributor?
Connect the ground side of your test lamp to the battery POSITIVE cable. Probe the TACH terminal on the dist. cap while a helper attempts to start the engine. The test lamp should blink repeatedly as the engine cranks.

What causes ignition module to burn out?
The leading cause of premature failure of an ignition coil is due to a worn or bad spark plug ignition cable. A bad spark plug ignition cable will have a much higher than normal resistance. This high resistance causes a very high amount of voltage to be generated from your ignition coil’s secondary winding.
Why do my coil packs keep failing?
Excessive heat and vibration can cause the insulating material to break down and create internal coil failure. Worn secondary ignition components such as spark plugs or wires can cause a coil work harder, require more voltage, and therefore significantly reduce the operating life of the coil.

How do you test the ignition control module inside a distributor?
Rotate the distributor center shaft by hand or by cranking the engine. Observe the distributor rotor as the engine is being cranked over. If the distributor rotor fails to turn, then the distributor or distributor gears are bad. The multimeter should read voltage alternating between battery voltage and zero.
What does an HEI module do?
With an electronic module, an HEI can safely operate at much higher current loads. More power applied across the primary circuit of the coil means the coil can apply greater spark energy to the spark plugs. This additional power ensures more complete combustion at both idle and at wide open throttle.
What are the symptoms of a bad ignition module?
Chevy Ignition Module Failure 1996 through 2005. In 1996 General Motors redesign the ignition module discussed above.
How to check if ignition control module is bad?
– Park your vehicle in a safe place and locate the ignition module. – Look under the dashboard. – Open the hood and remove the distributor cap using a Phillips screwdriver or ratchet and socket, but do not disconnect the spark plug wires from the distributor cap. – Look on one side of the distributor.
What causes ignition module failure?
Engine Vacuum Leak: This is caused by loose/broken vacuum hoses in the engine.
How to diagnose Hei distributer, no spark no start.?
The engine is not receiving fuel.