B2740
DTC B2740
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC B2740 00
-
Front Fog Lamp Switch Circuit Malfunction
Diagnostic Fault Information
Circuit/System Description
The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit, which illuminates the front fog lamps.
Conditions for Running the DTC
* The ignition is turned ON.
* Front fog lamp switch activated.
Action Taken When the DTC Sets
The front fog lamps malfunction.
Conditions for Setting the DTC
The front fog lamp switch is stuck on for more than 60 seconds.
Conditions for Clearing the DTC
The condition for setting the DTC is not longer present.
Reference Information
Schematic Reference
Fog Lights Schematics Fog Lights Schematics
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Front Fog Lamps Switch parameter while pressing and releasing the front fog lamps switch. The parameter should change between Active and Inactive when changing between the selected states.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
2. Ignition ON, verify that a test lamp illuminates between the 12 V reference circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal and the circuit fuse is open, test the signal circuit terminal 12 for a short to ground.
3. Verify the scan tool Front Fog Lamps Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the K9 BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the 12 V reference circuit terminal 1. Verify the scan tool Front Fog Lamps Switch parameter is Active.
• If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
5. If all circuits test normal, test or replace the S30 headlamp switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Headlamp Switch Replacement Service and Repair
* Control Module References Programming and Relearning for BCM replacement, programming and setup