P0654

DTC P0654

DTC Descriptor

DTC P0654
- Engine Speed Output Circuit

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






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.

Circuit/System Testing

1. 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.
2. Ignition ON, set the signal generator to generate a tachometer signal. Verify that the tachometer indicates a RPM reading.

• 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).

3. If all circuits test normal, test or replace the ECM/PCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

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