For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using the diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0654: Engine Speed Output CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Engine Speed Signal | B0560, P0654 | B0560, P0654 | B0560, P0654 | -- |
Circuit Description
The engine control module (ECM) creates the engine speed signal by pulsing the signal circuit to ground at the rate of 2 pulses per engine revolution. The ECM monitors the voltage at the engine speed signal circuit. If the ECM determines that the voltage is not within the normal operating range, the ECM sets a DTC.
Conditions for Running the DTC
| • | The engine speed is greater than 800 RPM. |
| • | The ignition voltage is greater than 9 volts but less than 18 volts. |
Conditions for Setting the DTC
| • | The ECM detects that the commanded state of the driver and the actual state of the signal circuit do not match. |
| • | The above condition is present for at least 5.0 seconds. |
Action Taken When the DTC Sets
| • | The ECM stores a DTC P0654 in memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM records the operating conditions at the time when the diagnostic test fails. The ECM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A history DTC clears after 40 malfunction free warm-up cycles. |
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECM. Install a signal generator and instrument panel tester between the engine speed signal circuit terminal 28 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.
| ⇒ | 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 and IPC replacement, setup, and programming
