2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 787

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 787

DTC B3891

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC B3891 02

- Trailer Fog Lamps Circuit Short to Ground

DTC B3891 05

- Trailer Fog Lamps Circuit Short to Battery or Open

Diagnostic Fault Information

Circuit/System Description

When the rear fog lamp switch is placed in the ON position, ground is applied to the auxiliary body control module (XBCM) through the rear fog

lamp switch circuit. The XBCM then applies voltage on the trailer fog lamp circuit to the trailer rear fog lamp.

Conditions for Running the DTC

The ignition is ON. Park lamps must be ON and the rear fog lamps must be commanded ON.

Conditions for Setting the DTC

The body control module (BCM) detects an open, short to ground, or short to voltage on the trailer rear fog lamp circuit while trying to apply a

voltage to the circuit.

Action Taken When the DTC Sets

The trailer rear fog lamps do not illuminate.

Conditions for Clearing the DTC

* The conditions for setting the DTC are no longer present.

* A history DTC clears after 100 malfunction-free ignition cycles.

* The BCM receives the clear code command from the scan tool.

Reference Information

Schematic Reference

Fog Lights Schematics (See: Diagrams/Electrical Diagrams/Lighting and Horns/System Diagram/Fog Lights Schematics)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

Exterior Lighting Systems Description and Operation (See: Lighting and Horns/Description and Operation/Exterior Lighting Systems Description

and Operation)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit