DTC P1600: Serial Communication Problem Between Pcm & TCM (Esteem 1.8L)
- Turn ignition on. Measure voltage between ground and PCM connector terminal E92-31 (Green/Yellow wire). If voltages toggle between 0-1.5 and 4-5 volts, check for intermittent problem or faulty PCM or TCM. Go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If voltages do not toggle between 0-1.5 and 4-5 volts, go to next step.
- If about 4-5 volts were present in previous step, check Green/Yellow wire for an open circuit, poor connection at PCM, or PCM power or ground circuit open. If wiring and circuits are okay, replace TCM. If about 4-5 volts were not present in previous step, go to next step.
- Turn ignition off. Disconnect TCM connector. Turn ignition on. Measure voltage between TCM connector E26-27 (Green/Yellow wire) and ground. If about 4-5 volts are present, check for open circuit at TCM power and ground circuits. If about 4-5 volts are not present, check for short to ground or poor connection in Green/White wire between PCM and TCM. If wiring and connection are okay, replace PCM. Retest system.