For 1990-2009 cars only
DTC Descriptor
DTC P0654: Engine Speed Output CircuitDiagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Engine Speed Signal Circuit | P0654 | P0654 | P0654 | -- |
Circuit Description
The powertrain control module (PCM) creates the engine speed signal by pulsing the circuit to ground. The engine control module (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 engine speed is greater than 400 RPM. |
| • | The ignition voltage is greater than 6 volts, but less than 18 volts. |
Conditions for Setting the DTC
| • | The ECM/PCM detects that the commanded state of the driver and the actual state of the signal circuit do not match. |
| • | The above condition exists for a minimum of 5 seconds. |
Action Taken When the DTC Sets
| • | The ECM/PCM stores the DTC information in memory when the diagnostic test runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM/PCM records the operating conditions at the time when the diagnostic test fails. The ECM/PCM stores this information in the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | A history DTC is cleared after 40 consecutive malfunction-free warm-up cycles. |
| • | The ECM/PCM receives the clear code command from the scan tool. |
Reference Information
Schematic Reference
| • | Engine Controls Schematics for the 4.2L engine |
| • | Engine Controls Schematics for the 5.3L engine |
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECM/PCM. Install a signal generator and instrument panel tester between the engine speed signal circuit and ground.
- Ignition ON, set the signal generator to generate a tachometer signal. Verify that the tachometer indicates a RPM reading.
- If all circuits test normal, test or replace the ECM/PCM.
| ⇒ | If no RPM reading is present, test the signal circuit for an open/high resistance, a short to voltage, or a short to ground. If the circuit tests normal, replace the instrument panel cluster (IPC). |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for the ECM/PCM and IPC replacement, setup, and programming
