Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Transmission will not shift gears.

Possible Causes

- Low transmission fluid level - Dirty transmission fluid - Faulty low coast brake solenoid valve - Low coast brake solenoid valve harness or connectors - Low coast brake solenoid valve circuit is open or shorted

When Detected

The P0773 code is detected when the gear required by the ECM does not match the actual gear when vehicle is driven.

Description

Low coast brake solenoid valve is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position.