Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit Description
The Ignition Control Module (ICM) sends signals that PCM requires for fuel control and spark advance calculations. At start of engine crank, ICM controls spark advance (by-pass mode). When the second 3X reference pulse is recognized by the PCM, PCM applies 5 volts to by-pass circuit, commanding ICM to switch spark advance to PCM control (IC mode). If PCM detects an open in the IC circuit, DTC will set. Engine will start and may run in by-pass mode timing.
Conditions for setting DTC:
- Engine running.
- PCM detects an open in by-pass circuit.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.