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DTC codes / P27xx · Transmission / P277B
P277B indicates that the transmission control module (TCM) has detected a performance fault in the driver circuit for the electric auxiliary transmission fluid pump, typically used in hybrid and stop-start vehicles to maintain fluid pressure when the engine is off. The computer monitors the circuit for expected voltage or current behavior and sets this code when the actual signal deviates from the commanded value, indicating a problem with the pump motor, wiring, or control module.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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