Checking PCM Power & Ground Circuits
Possible Causes:
- PCM Fused B+ Circuit
- PCM Fused Ignition Switch Output Circuit
- PCM Ground Circuits
Testing
- Turn ignition off. Disconnect PCM harness connectors. PCM is located on left side of engine compartment, near air filter housing. See Fig 1 . Connect a test light between ground and fused battery voltage circuit (Red/Tan 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 3 . 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 positive battery voltage, probe terminal No. 10 (Black/Tan wire) at PCM C1 harness connector. Also probe terminal No. 50 (Black/Tan Green wire) at PCM C2 harness connector. If test light illuminates brightly at both terminals, ground circuits are okay. Test is complete. If test light does not illuminate brightly at one or both terminals, repair open in appropriate Black/Tan wire between PCM and ground.