DTC P1601 - Communication Line Error (Automatic Transmission): Condition

DTC is set when signal voltage from Transmission Control Module (TCM) to Engine Control Module (ECM) is too high. Possible causes are:

• Open or short circuit between terminal No. 1C on TCM and terminal No. 1R on ECM.
• Open or short circuit between terminal No. 2O on TCM and ignition switch.
• Open circuit between terminal No. 2P on TCM and ground.