DTC B0540. GMC Truck TopKick C-Series (Conventional) C4/C5 2009

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2009 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B0540

Diagnostic Instructions

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

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

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

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Vehicle Speed Signal	B0540, P0608	B0540, P0608	B0540, P0608	--

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 serial data message from the ECM/PCM indicating the vehicle speed. The IPC uses the serial data message for diagnostic purposes.

Conditions for Running the DTC

•	The IPC receives a serial data message from the ECM/PCM 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 4K PPM 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 a DTC B0540 in memory.

Conditions for Clearing the DTC

•	The history DTC clears after 100 malfunction free warm-up cycles.

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

Reference Information

Schematic Reference

•	Instrument Cluster Schematics

•	Engine Controls Schematics for the 6.6L engine

•	Engine Controls Schematics for the 7.2L engine

•	Engine Controls Schematics for the 7.8L engine

•	Engine Controls Schematics for the 8.1L engine

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 Testing

Ignition OFF, disconnect the X1 or X2 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)

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.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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