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.
C-4, Ignition Control Circuit
An open or short to ground in Ignition Control (IC) or by-pass circuit will cause ECM to turn on Malfunction Indicator Light (MIL) and confirm fault by setting a related trouble code. Refer to appropriate G - GASOLINE TESTS W/ CODES article in the ENGINE PERFORMANCE section below.
- G - TESTS W/CODES - 4.3L
- G - TESTS W/CODES - 5.0L
- G - TESTS W/CODES - 5.7L
- G - TESTS W/CODES - 7.4L
NO RELATED
Use the Manual With the Right Hardware
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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.