B2540
DTC B2540
CIRCUIT DESCRIPTION
The rear fog lamp switch signal circuit is grounded momentarily by pressing the rear fog lamp switch. The body control module (BCM) energizes the rear fog lamp relay by applying battery voltage to the rear fog lamp relay control circuit. When the rear fog lamp relay is energized, battery voltage is applied via the REAR FOG/ALDL TOP SW fuse to the rear fog lamp supply voltage circuit which illuminates the rear fog lamps.
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC B2540 Rear Fog Lamps Control Circuit
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information. DTC Symptom Description
CONDITIONS FOR RUNNING THE DTC
Battery voltage must be between 9-16 volts.
CONDITIONS FOR SETTING THE DTC
- DTC B2540 02 will set when the BCM detects a short to ground in the rear fog lamp relay control circuit.
- DTC B2540 05 will set when the BCM detects an open or short to voltage in the rear fog lamp relay control circuit.
ACTION TAKEN WHEN THE DTC SETS
- When DTC B2540 02 is present, the rear fog lamps will not operate when the park lamps are ON and the rear fog lamp switch is active.
- When DTC B2540 05 is present, the rear fog lamps and/or the rear fog lamp indicator will be ON at all times or will not operate.
CONDITIONS FOR CLEARING THE DTC
- The condition responsible for setting the DTC no longer exists.
- You issue a scan tool CLEAR DTCs command.
- A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.
DIAGNOSTIC AIDS
Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Diagnostic Aids. Component Tests and General Diagnostics
TEST
