The TCM (Transmission Control Module) is a device that collects data and processes various signals from the vehicle’s transmission to regulate transmission shifting. On an ongoing basis, the TCM works with a lot of parts that depend on it, for example, the engine, Brake Pedal Position Sensor, Transmission Fluid Temperature Sensor, Turbine Sensor, and Throttle Position Sensor.
In modern systems, transmission is electronically controlled, so the Transmission Control Module regulates transmission performance so that gear changes are made consistently and accurately.
The P1701 OBD2 diagnostic code is set when the TCM power is interrupted or turned off, for example, if the battery is disconnected or if the self-test memory function is stopped.