DTC P1600 - Pcm & TCM Serial Communication Fault
- Turn ignition on. Using a voltmeter, measure voltage (backprobe) between ground and PCM harness connector "B", terminal No. 8 (Blue wire). See Figure . If reading is zero volts, go to next step. If reading toggles between 0-5 volts, check for an intermittent problem. See TESTS W/O CODES article. If reading is about 5 volts, check for open Blue wire. Repair as necessary. If wire is okay, replace Transmission Control Module (TCM). Retest system.
- Turn ignition off. Disconnect TCM harness connectors. Turn ignition on. Using a voltmeter, measure voltage (backprobe) between ground and PCM harness connector "B", terminal No. 8 (Blue wire). If reading is about 5 volts, replace TCM. If reading is not as specified, check Blue wire for short to ground. Repair as necessary. If wire is okay, replace PCM. Retest system.