Buick Regal: DTC B2740
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 B2740 00
Front Fog Lamp Switch Circuit Malfunction
Diagnostic Fault Information
1. Front Fog Switch Malfunction
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.
Conditions for Setting the DTC
The BCM detects the fog lamp switch is continuously active.
Action Taken When the DTC Sets
Front fog lamps will be continuously illuminated.
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 50 ignition cycles.
Conditions for Clearing the DTC
The condition for setting the DTC is not longer present.
Reference Information
Schematic Reference
Fog Lights Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
Exterior Lighting Systems 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 Verification
Ignition ON, observe the scan tool Front Fog Lamps Switch parameter while
turning the front fog lamps
switch ON and OFF. The parameter should change between Active and Inactive.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
2. Ignition ON, test for greater than 10V between the 12 V reference circuit
terminal 1 and ground.
- If less than the specified range, test the 12 V reference circuit for a
short to ground or an
open/high resistance. If the circuit tests normal, replace the K9 BCM.
3. Test for 0.4K Ω to 1K Ω between the signal circuit terminal 12 and ground.
- If greater than the specified range, test the signal circuit for a short
to voltage or an
open/high resistance. If the circuit tests normal, replace the K9 BCM.
- If less than the specified range, test the signal circuit for a short to
ground. If the circuit tests
normal, replace the K9 BCM.
4. If all circuits test normal, test or replace the S30 headlamp switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic
procedure.
- Headlamp Switch Replacement
- Control Module References for BCM replacement, setup and programming
READ NEXT:
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.
Diag
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.
Diag
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.
Diag
SEE MORE:
SPECIFICATIONS
WHEEL ALIGNMENT SPECIFICATIONS (4-DOOR HATCHBACK 68)
Alignment Condition: Full tank of fuel, no passengers and placed on flat
level surface.
WHEEL ALIGNMENT SPECIFICATIONS (4-DOOR STATION WAGON 35)
Alignment Condition: Full tank of fuel, no passengers and placed on flat
level surfa
Removal Procedure
WARNING: Refer to: Inflatable Restraint Module Handling and Scrapping.
WARNING: Refer to: SIR Inflator Module Handling and Storage Warning.
WARNING: Refer to: SIR Warning.
1. Disable the SIR system. Refer to SIR Disabling and Enabling.
2. Steering Column Upper Trim Cover Replaceme