For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category

### DTC Descriptors

DTC B0654: Engine Speed Signal Range/Performance

### Circuit/System Description

The instrument panel cluster (IPC) receives engine speed data from the ECM via the serial data circuit for display in the IPC. The ECM sends the engine speed information to the steering column control module (SCCM) via the serial data circuit. The SCCM sends the engine speed information to the IPC via the serial data circuit. The IPC uses the engine speed data to display the tachometer.

### Conditions for Running the DTC

• | The engine is running.

• | The ignition voltage is between 9-18 volts.

### Conditions for Setting the DTC

• | The ECM detects that the engine speed information is invalid.

• | The above condition must be present for a minimum of 8 seconds.

### Action Taken When the DTC Sets

The ECM records the operating conditions at the time the diagnostic fails. The 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.

### Reference Information

#### Schematic Reference

Instrument Cluster Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Instrument Cluster Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information.

### Circuit/System Verification

1. Ignition ON and the scan tool installed, perform the IPC Engine Speed Control Test from the ECU Control menu. Verify that the tachometer pointer moves from the minimum value to the maximum value as commanded.

⇒ | If the tachometer does not perform the Engine Speed Control Test, replace the IPC.

2. Verify that the tachometer value matches the scan tool Engine Speed parameter in the ECM Engine Data List.

⇒ | If the tachometer is incorrect, test or replace the IPC.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for the IPC replacement, setup and programming.