What does it mean?
This is a generic diagnostic code (DTC) and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Buick, Cadillac, Chevrolet, Ford, GMC, Opel, Peugeot, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
A stored code P0654 means that the Powertrain Control Module (PCM), or one of the other associated controllers, has detected an anomaly in the engine speed (RPM) output circuit.
The engine RPM output circuit is responsible for providing an engine RPM output signal to the dashboard tachometer and other controllers. The PCM receives engine speed data from the engine’s camshaft and crankshaft sensors. This data is primarily used to calculate and monitor engine operation and is then transmitted to the tachometer and other controllers (to which it is instrumental).
If a problem is detected while monitoring the engine speed output circuit, a P0654 code will be stored, and a Malfunction Indicator Lamp (MIL) may illuminate.
A tachometer indicating engine speed:
P0654 Engine Tachometer
How severe is this DTC?
A P0654 should be classified as severe because it could lead to transmission shifting issues and/or problems with the Anti-lock Braking System (ABS) and Traction Control System (TCS).
What are some of the symptoms of the code?
Symptoms of a P0654 trouble code may include:
Irregular or harsh transmission shifting
ABS or TCS problems
Engine operation issues
Stored ABS and TCS codes
What are some common causes of the code?
Causes
of this code may include:
PCM programming error
Faulty controller or PCM
Open or shorted circuit between the PCM and the dashboard or other controllers
What are the troubleshooting steps for P0654?
If there are any Vehicle Speed Sensor (VSS) codes, engine speed input codes, camshaft position sensor codes, or crankshaft position sensor codes; diagnose and repair those before attempting to diagnose a stored P0654.
Consult your vehicle’s information source for Technical Service Bulletins (TSB) that match the stored code, the vehicle (year, make, model, and engine), and the symptoms presented. If you find the appropriate TSB, it may provide helpful diagnostic information.
A diagnostic scanner, a digital volt/ohmmeter, and an oscilloscope will be necessary to accurately diagnose a P0654 code. A reliable source of vehicle information will also be required.
Start by connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and freeze frame data. You’ll want to note this information, just in case the code proves to be intermittent.
After recording all relevant information, clear the codes and test-drive the vehicle (if possible) until the code resets or the PCM enters readiness mode.
If the PCM enters readiness mode, the code is intermittent and will be even more difficult to diagnose. The condition that caused the P0654 to be stored may need to worsen before an accurate diagnosis can be made. On the other hand, if the code does not reset and no driving symptoms manifest, the vehicle may be operating normally.
If the P0654 is immediately reset, proceed with a visual inspection of the wiring and connectors related to the system. Harnesses that are broken or disconnected should be repaired or replaced as necessary.
If the wiring and connectors appear functional, use your vehicle information source to obtain the appropriate wiring diagrams, connector face views, connector pinout diagrams, and diagnostic flowcharts.
Once you have the correct information, use your DVOM and oscilloscope to test the engine RPM output at the appropriate pin of the PCM connector. If no RPM output signal is found, suspect a faulty PCM or a PCM programming error.
If an engine RPM output signal is found at the PCM connector, test the corresponding circuit (as presented) at the dashboard tachometer. If the tachometer signal is not found, you have an open circuit between the PCM and the dashboard. Repair or replace the circuit and retest.
If a P0654 code is stored and the tachometer is operational, suspect a faulty PCM or a PCM programming error