The OBD-II trouble code P0654 indicates a malfunction in the engine RPM output circuit in the vehicle.
The engine RPM output circuit is responsible for transmitting the engine speed signal to various vehicle systems, such as the instrument cluster, the transmission control module, and the anti-lock brake system. A malfunction in this circuit can cause a variety of issues, such as inaccurate speedometer readings, improper shifting of the transmission, and a malfunctioning anti-lock brake system.
In order to diagnose and repair the issue, a qualified technician will need to use specialized diagnostic equipment to communicate with the vehicle's engine control module (ECM) and identify the root cause of the engine RPM output circuit malfunction. The technician may need to test the wiring and connectors associated with the engine RPM output circuit, as well as perform tests on the ECM itself.
Once the root cause of the issue is identified, the technician may need to repair or replace the wiring and connectors associated with the engine RPM output circuit, or repair or replace the ECM if it is determined that the engine RPM output circuit in the ECM is at fault.
It is important to address these issues promptly, as a malfunctioning engine RPM output circuit can cause a variety of issues that may affect the drivability and safety of the vehicle.