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. See Fig 1 . Connect a test light between ground and fused battery voltage circuit (Red wire) at PCM C1 harness connector terminal No. 29. 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. 11. 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. 9. See Fig 2 .
- Black/Tan wire at PCM C1 harness connector terminal No. 18.
- Black/Yellow wire at PCM C4 harness connector terminal No. 12. See Fig 3 .
- Black/Red wire at PCM C4 harness connector terminal No. 13.
- Black/Red wire at PCM C4 harness connector terminal No. 14.
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.