Checking Powertrain Control Module (PCM) Power & Ground Circuits (Wrangler)
- Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Inspect connector for damaged pins, corrosion and loose terminals. Repair connector as necessary. Using a test light connected to ground, probe terminal A22 (Red/White wire) at PCM C1 harness connector. See Fig 1
. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused B(+) circuit (Red/White wire) between fuse No. 9 (30-amp) in Power Distribution Center (PDC) and PCM. PDC is located in right side of engine compartment, next to battery. See WIRING DIAGRAMS article. Also check fuse No. 9 in PDC.
- Turn ignition on. Using a test light connected to ground, probe terminal C3 (Dark Blue/Yellow wire) at PCM C3 harness connector. See Fig 1
. If test light illuminates brightly, power circuits are okay. Go to next step. If test light does not illuminate brightly, repair open fused ignition switch output circuit (Dark Blue/Yellow wire) between fuse No. 12 (10-amp) in fuse block and PCM. Fuse block is located behind glove box. Also check fuse No. 12 in fuse block.
- Turn ignition off. Using a test light connected to positive battery voltage, probe terminals A31 (Black/Tan wire) and A32 (Black/Tan wire) at PCM C1 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. Ground connection is located on right rear of cylinder block.
Courtesy of DAIMLERCHRYSLER CORPORATION