Checking Powertrain Control Module (PCM) Power & Ground Circuits (Grand Cherokee)
- Turn ignition off. Disconnect PCM Black C1 connector. 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 No. 22 (Red/Black wire) at PCM C1 harness connector. See Figure . If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused B(+) circuit (Red/Black wire) between fuse No. 19 (10-amp) in Power Distribution Center (PDC) and PCM. PDC is located in right side of engine compartment, next to battery. Also check fuse No. 19 in PDC. See WIRING DIAGRAMS article.
- Turn ignition on. Using a test light connected to ground, probe terminal No. 2 (Orange/Dark Blue wire) at PCM C1 connector. See Figure . If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair open fused ignition switch output circuit (Orange/Dark Blue wire) between fuse No. 12 (10-amp) in junction block and PCM. Junction block is located under left side of instrument panel. Also check fuse No. 12 in junction block.
- Turn ignition off. Using a test light connected to positive battery voltage, probe terminals No. 31 (Black/White wire) and No. 32 (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 Black/White and/or Black/Tan wire between PCM and ground. Ground connection is located on right side of cylinder block.