Speedometer and/or Odometer Inaccurate or Inoperative

Speedometer and/or Odometer Inaccurate or Inoperative (4.8L, 5.3L, 6.0L, 6.2L, 7.0L Engines)

Diagnostic Instructions

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

Circuit Description

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

Reference Information
Schematic Reference

* Instrument Cluster Schematics (Instrument Cluster Schematics)
* Diagnostic Starting Point - Engine Controls (Initial Inspection and Diagnostic Overview)
* Automatic Transmission Controls Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Instrument Cluster Description and Operation (Description and Operation)
* Engine Control Module Description (Engine Control Module Description)
* Electronic Component Description (TCM) (Electronic Component Description (TCM))Electronic Component Description (PCM) (Electronic Component Description (PCM))

Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) 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 both the vehicle speed signal circuit terminal B9 for an open/high resistance and the high-front signal circuit terminal 16 at the transmission control module (TCM) for an open/high resistance, short to voltage, or short to ground.

4. If the circuits test normal, test or replace the IPC.

Repair Instructions

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

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