P0654 Engine RPM Output Circuit Malfunction
OBD-II Trouble Code Technical Description
Engine RPM Output Circuit Malfunction
What does that mean?
This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). That 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 year, make, model, and powertrain configuration.
A stored code P0654 means that the powertrain control module (PCM), or one of the other related controllers, has detected a discrepancy in the engine RPM (revolutions per minute) output circuit.
The engine RPM output circuit is responsible for providing an engine RPM output signal to the instrument panel tachometer and other controllers. The PCM receives engine RPM data from the engine camshaft and crankshaft sensors. This data is used primarily for calculating and monitoring engine drivability then output to the tachometer and other controllers (to which it is instrumental).
If a problem is detected in monitoring the engine RPM output circuit, a code P0654 will be stored and a malfunction indicator lamp (MIL) may be illuminated.
A tachometer showing engine RPM:
What is the severity of this DTC?
A P0654 should be categorized as severe because it could result in transmission shifting issues and/or antilock brake system (ABS) and electronic traction control system (TCS) problems.
What are some of the symptoms of the code?
Symptoms of a P0654 trouble code may include:
Erratic or harsh transmission shifting ABS or TCS problems Engine drivability issues Stored ABS and TCS codesWhat are some of the common causes of the code?
Causes for this code may include:
PCM programming error Faulty controller or PCM Open or shorted circuit between the PCM and the instrument panel or other controllersWhat are some P0654 troubleshooting steps?
If there are vehicle speed sensor (VSS) codes, engine RPM input codes, camshaft position sensor, or crankshaft position sensor codes present; diagnose and repair those before attempting to diagnose a stored P0654.
Consult your vehicle information source for technical service bulletins (TSB) that replicate the code stored, vehicle (year, make, model, and engine), and symptoms exhibited. If you find the appropriate TSB, it may yield helpful diagnostic information.
A diagnostic scanner, a digital volt/ohmmeter, and an oscilloscope will be necessary to accurately diagnose a code P0654. A reliable source of vehicle information will also be required.
Begin by connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and freeze frame data. You will want to write this information down, just in case the code proves to be an intermittent one.
After recording all pertinent information, clear the codes and test drive the vehicle (if possible) until the code is reset 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, which caused the P0654 to be stored, may need to worsen before an accurate diagnosis can be reached. On the other hand, if the code fails to reset and there are no drivability symptoms exhibited, the vehicle can be operated normally.
If the P0654 is immediately reset, proceed with a visual inspection of system related wiring and connectors. Harnesses that have been broken of unplugged should be repaired or replaced as required.
If wiring and connectors appear functional, use your source of vehicle information to obtain the appropriate wiring diagrams, connector face views, connector pin-out charts, and diagnostic flow charts.
Once you have the correct information, use your DVOM and oscilloscope to test engine RPM ou
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