P0654

DTC P0654

DTC DESCRIPTOR
DTC P0654: Engine Speed Output Circuit




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The engine control module (ECM) or the powertrain control module (PCM) creates the engine speed signal by pulsing the engine speed signal circuit to ground. The ECM/PCM monitors the voltage on the engine speed signal circuit. If the ECM/PCM determines that the voltage is not within the normal operating range, the ECM/PCM sets a DTC.

CONDITIONS FOR RUNNING THE DTC
- The ignition is ON, with the engine running.
- The system voltage is between 9-16 volts.
- The engine speed is more than 400 RPM.

CONDITIONS FOR SETTING THE DTC
- The ECM/PCM detects that the commanded state of the driver and the actual state of the signal do not match.
- The above condition is present for greater than 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
The PCM/ECM records the operating conditions at the time that the diagnostic test fails. The PCM/ECM displays the failure information in the Failure Records on the scan tool.

CONDITIONS FOR CLEARING THE DTC
- The DTC becomes history when the conditions for setting the DTC are no longer present.
- The history DTC clears after 40 malfunction free warm-up cycles.
- The PCM/ECM receives a clear code command from the scan tool.

CIRCUIT/SYSTEM TESTING
1. Install a scan tool
2. Start the engine
3. With the scan tool, observe the Engine Speed parameter in the ECM/PCM Engine Data list.
- If the engine speed parameter matches the tachometer display, check for a poor connection at the harness connector of the ECM/PCM.
4. Turn OFF the ignition.
5. Disconnect the ECM/PCM connector C000
6. With the ignition ON, install one lead of the signal generator to the engine speed signal circuit at the ECM/PCM connector and the other lead to a good ground.
7. Set the signal generator to generate a tachometer signal and observe the vehicle tachometer.
- If the vehicle tachometer indicates an engine RPM, check for a poor connection at the harness connector of the ECM/PCM.
- If the connector is normal, replace the ECM/PCM.
- If the vehicle tachometer does not indicate an engine RPM, test the engine speed signal circuit for a short to voltage, short to ground or an open.
- If the engine speed circuit tests normal, replace the IPC.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification Verification Tests

Control Module References for IPC and ECM/PCM replacement, setup and programming