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.
Checking PCM Power & Ground Circuits
- Turn ignition off. Disconnect PCM harness connectors. See Fig 1 . Connect a test light between ground and fused battery voltage circuit (Red/White wire) at PCM C2 harness connector terminal No. 46. See Fig 2 . If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open in fused battery voltage circuit.
- Turn ignition on. Connect a test light between ground and fused ignition switch output circuit (Dark Blue/White wire) at PCM C1 harness connector terminal No. 20. See Fig 2 . If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open in fused ignition switch output circuit.
- Turn ignition off. Using a test light connected to battery positive, individually probe the following ground circuits:
- Black/Tan wire at PCM C1 harness connector terminal No. 10.
- Black/White wire at PCM C2 harness connector terminal No. 47.
- Black/Tan wire at PCM C2 harness connector terminal No. 50.
If test light illuminates at each ground circuit, ground circuits are okay. Test is complete. If test light does not illuminate at each ground circuit, repair open in appropriate ground circuit.
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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.
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