Speedometer and/or Odometer Inaccurate or Inoperative (4.2L Engine)

Speedometer and/or Odometer Inaccurate or Inoperative (4.2L Engine)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using the diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Circuit Description

The instrument panel cluster (IPC) receives the vehicle speed information from the powertrain control module (PCM) through the vehicle speed signal circuit. The PCM converts the data from the vehicle speed sensor to a 4,000 pulses/mile signal. The PCM also sends a class 2 message to the IPC indicating the vehicle speed.

Reference Information
Schematic Reference

* Instrument Cluster Schematics (Instrument Cluster Schematics)
* Engine Controls Schematics ([1][2]Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Component Connector End Views)
Description and Operation

* Instrument Cluster Description and Operation (Description and Operation)
* Engine Control Module Description (Engine Control Module Description)

Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Testing

1. Ignition ON, perform the segments test with the scan tool.

• If not all of the segments illuminate, replace the IPC.

2. Raise the vehicle drive wheels. Refer to Lifting and Jacking the Vehicle (Service and Repair).
3. Engine ON, transmission in drive, verify the scan tool Vehicle Speed Sensor parameter matches the speedometer display.

• If the Vehicle Speed Sensor parameter does not match the speedometer display, test the vehicle speed signal circuit terminal B9 for an open/high resistance.

4. If the circuit tests normal, test or replace the IPC.

Repair Instructions

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

Control Module References (Control Module References) for the IPC replacement, setup, and programming