P1605 - Automatic Transaxle Diagnostic Communication Line

The Transaxle Control Module (TCM) circuits are monitored by the Powertrain Control Module (PCM). The test fails when an incorrect signal is sent to the PCM from the TCM.

Possible Causes:
- The communication line circuit between the TCM and the PCM is shorted or open
- Dead or weak battery
- The TCM

Diagnostic Aids:
Check the harnesses and connectors.