TB1 - DTC 1780

Diagnostic Trouble Code (DTC) 1780 indicates the Transmission Control Switch (TCS) was not cycled during Key On Engine Running (KOER) Self-Test.

Possible Causes:
- TCS damaged or switch not cycled during Self-Test.
- Shorted or open harness.
- Damaged Powertrain Control Module (PCM).

- Did TCS cycle during Self-Test?

YES -- GO to TB2. TB2 - Check Transmission Control Switch (TCS) Circuit Voltage

NO -- RERUN KOER Self-Test to cycle TCS.