Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Transmission shift shock

Possible Causes

- Low transmission fluid level - Dirty transmission fluid - Faulty shifting solenoid valve - Shifting solenoid valve harness or connectors - Shifting solenoid valve circuit is open or shorted

When Detected

The P0780 codes is detected when no rotation change occurs between input (turbine revolution sensor) and output (revolution sensor) and shifting time is long or when shifting ends immediately or when engine revs up unusually during shifting.

Description

The Transmission Control Module (TCM) monitors the transmission mechanical shifting through various sensors. This malfunction is detected when the A/T does not shift as instructed by the TCM. This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking,improper solenoid valve operation, etc.