2010 Cadillac Truck SRX FWD V6-3.0L Page 729

2010 Cadillac Truck SRX FWD V6-3.0L Page 729

DTC B3891 04

- Trailer Fog Lamps Circuit Open

Diagnostic Fault Information

Circuit/System Description

The trailer brake control module will receive a serial data message from the BCM indicating that the vehicle rear fog lamps have been activated.

The trailer brake control module will then apply system voltage to the trailer fog lamps through their respective voltage supply circuits.

Conditions for Running the DTC

When the trailer fog lamps are turned on.

Conditions for Setting the DTC

B3891 02

The trailer brake control module detects a short to ground on the trailer fog lamp control circuit.

B3891 04

The trailer brake control module detects an open/high resistance on the trailer fog lamp control circuit.

Action Taken When the DTC Sets

The trailer fog lamps will be inoperative.

Conditions for Clearing the DTC

* The DTC will be current for as long as the fault is present.

* When the fault is no longer present, the DTC will be a history DTC.

* A history DTC will clear after 40 ignition cycles.

Reference Information

Schematic Reference

Trailer Connector/Provision Schematics (See: Diagrams/Electrical Diagrams/Starting and Charging/Power and Ground Distribution/System

Diagram/Trailer Connector/Provision Schematics)

Connector End View Reference

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

Description and Operation

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

Electrical Information Reference

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

Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic

Procedures/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General

Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)

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

Repairs/Wiring Repairs)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, observe the function of the trailer fog lamps while commanding the Trailer Fog Lamp ON and OFF with a scan tool. The trailer fog

lamps should turn ON and OFF while changing between the commanded states.