Service Information

Orlando

DTC B2540

Diagnostic Instructions

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

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

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

DTC Descriptor

DTC B2540 01: Rear Fog Lamps Control Circuit Short to Battery

DTC B2540 02: Rear Fog Lamps Control Circuit Short to Ground

DTC B2540 04: Rear Fog Lamps Control Circuit Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Rear Fog Lamps Control	B2540 02	B2540 04	B2540 01	-

The body control module (BCM) energises the rear fog lamp by applying voltage to the rear fog lamp control circuit. When the rear fog lamp control circuit is energised the rear fog lamp is illuminated.

Conditions for Running the DTC

Rear fog lamp activated

Conditions for Setting the DTC

B2540 01

The BCM detects a short to voltage on the control circuit.

B2540 02

The BCM detects a short to ground on the control circuit.

B2540 04

The BCM detects an open control circuit.

Action Taken When the DTC Sets

The rear fog lamp are inoperative.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

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 Verification

Ignition ON, perform the Rear Fog Lamps Relay test. The rear fog lamp should be ON/OFF when changing between the commanded states.

Circuit/System Testing

Ignition OFF, disconnect the harness connector at the E29R Fog Light - Rear.
Test for less than 5 Ω between the ground circuit harness connector terminal 3 and ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance.

Connect a test lamp between the control circuit harness connector terminal 2 and ground.
Ignition ON, perform the Rear Fog Lamps Relay test. The test lamp should be ON/OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 Body Control Module.

If all circuits test normal, test or replace the E29R Fog Light - Rear.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Reversing and Rear Fog Light Replacement

•	Control Module References for BCM replacement, setup and programming