B0540

DTC B0540

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this 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.



DTC Descriptor
DTC B0540
- Speedometer Circuit




Diagnostic Fault Information






Circuit/System Description

The engine control module (ECM) creates the vehicle speed signal by pulsing the vehicle speed signal circuit to ground at a rate of 4KPPM. The instrument panel cluster (IPC) converts the 4KPPM vehicle speed signal to a speedometer position to indicate the vehicle speed. The IPC also receives from the ECM a serial data message indicating the vehicle speed. The IPC uses the serial data vehicle speed information from the ECM for diagnostics purposes.


Conditions for Running the DTC

* The IPC receives a serial data message from the ECM indicating that the vehicle speed is greater than 10 km/h (6 mph).
* The ignition voltage is between 9-18 volts.



Conditions for Setting the DTC

* The IPC does not detect a 4KPPM signal on the vehicle speed signal circuit.
* The condition above must be present for a minimum of 5 seconds.



Action Taken When the DTC Sets

The IPC stores DTC B0540 in memory.


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 (Instrument Cluster Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Instrument Cluster Description and Operation (Description and Operation)
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)


Circuit/System Testing

1. Ignition ON, the scan tool installed, perform the IPC Gage Sweep Test in the IPC Output Controls. Verify the speedometer dial moves from the minimum to the maximum position and back to the speedometer minimum position.

• If the speedometer does not perform the IPC Gage Sweep Test, replace the IPC.

2. Ignition OFF, disconnect the X1 harness connector at the ECM.
3. Ignition ON, test for 9-11 volts between the vehicle speed signal circuit terminal 57 and ground.

• If less than 9 volts, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the IPC.


• If greater than 11 volts, test the circuit for a short to voltage.

4. If all circuit tests normal, test or replace the ECM.



Repair Instructions

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


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