Checking Powertrain Control Module (PCM) Power & Ground Circuits (Wrangler)
- 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. If connector is okay, measure voltage between ground and terminal A22 (Red/White wire) at PCM C1 connector. See Fig 1
. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, 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.
- Turn ignition on, with engine off. Measure voltage between ground and terminal A2 (Dark Blue wire) at PCM C1 connector. See Fig 1
. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open fused ignition switch output circuit (Dark Blue wire) between fuse No. 12 (10-amp) in fuse block and PCM. Fuse block is located behind glove box.
- Turn ignition off. Measure resistance between ground and terminal A31 (Black/Tan wire) at PCM C1 connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black/Tan wire between PCM and ground. Ground connection is located on right rear of cylinder block (2.5L) or right front of cylinder block, near generator (4.0L).
- Measure resistance between ground and terminal A32 (Black/Tan wire) at PCM C1 connector. If resistance is less than 5 ohms, ground circuit is okay. Test is complete. If resistance is more than 5 ohms, repair open in Black/Tan wire between PCM and ground. Ground connection is located on right rear of cylinder block (2.5L) or right front of cylinder block, near generator (4.0L).
Courtesy of DAIMLERCHRYSLER CORPORATION