The engine control module (ECM)/powertrain control module (PCM) creates the vehicle speed signal by pulsing the signal circuit to ground at a rate of 4K PPM. The instrument panel cluster (IPC) converts the 4K PPM signal to a speedometer position. The IPC also receives a class 2 message from the ECM/PCM indicating the vehicle speed.

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Verify that the odometer operates properly.

⇒	If the odometer does not operate properly, replace the IPC.

2. Ignition OFF, disconnect the harness connector at the ECM/PCM. Install a signal generator and instrument panel tester between ground and the following vehicle speed signal circuit:

•	Terminal 82 (LF8)

•	Terminal 36 LF6)

•	Terminal 50 (L18)

3. Ignition ON, set the signal generator to generate a speedometer signal. Verify that the vehicle speedometer indicates a reading.

⇒	If no speedometer 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 IPC.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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