Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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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.