• | 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 |
---|---|---|---|---|
Front Fog Lamp Switch Signal | 1 | 2 | 2 | -- |
Fog Lamp Relay Control | 2 | 1 | 1 | -- |
Fog Lamp Control | 2 | 2 | 1 | -- |
Fog Lamp Ground | -- | 2 | 2 | -- |
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The vehicle fog lamps are controlled by the body control module (BCM) based on an input from the fog lamp switch. The fog lamp switch is a momentary switch integrated with the headlamp switch. When activated, the fog lamp switch provides a momentary ground to the BCM via the front fog lamp switch signal circuit, indicating the fog lamps are requested ON.
The BCM controls the fog lamps based on the inputs explained above. When a fog lamp request is received, the BCM grounds the fog lamp relay control circuit. This energizes the FOG LP relay. With the relay energized, B+ is applied to both fog lamps.
Exterior Lighting Systems Description and Operation
• | Circuit Testing |
• | Wiring Repairs |
Control Module References for Scan Tool Information
⇒ | If the parameter does not cycle between the specified values, refer to Fog Lamp Switch Circuit Malfunction. |
⇒ | If the fog lamps do not cycle between the commanded states, refer to Fog Lamp Circuit Malfunction. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the BCM. |
⇒ | If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the FOG LPS fuse is open, test the control circuit terminal A9 for a short to ground. If the circuit tests normal, test or replace the FOG LP relay. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If the fog lamps do not activate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the applicable fog lamp bulb. |
⇒ | 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 an 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 |