• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Rear Fog Lamp Relay Control | B2540 02 | B2540 05 | B2540 05 | -- |
Rear Fog Lamp Voltage Supply | 1 | 1 | 1 | -- |
Rear Fog Lamp Switch Signal | 1 | 1 | -- | -- |
Rear Fog Lamp Relay Voltage Supply | 1 | 1 | -- | -- |
Fog Lamp - LR Ground | -- | 1 | 1 | -- |
Fog Lamp - RR Ground | -- | 1 | 1 | -- |
Fog Lamp Switch Ground | -- | 1 | 1 | -- |
1. Rear Fog Lamps Malfunction |
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 ground 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.
Battery voltage must be between 9-16 volts.
This DTC will set when the BCM detects a short to ground in the rear fog lamp relay control circuit.
This DTC will set when the BCM detects an open or short to voltage in the rear fog lamp relay control circuit.
• | 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. |
• | The condition responsible for setting the DTC no longer exists. |
• | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. |
Exterior Lighting Systems Description and Operation
Control Module References for scan tool information
⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the BCM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |