Front Fog Lamps Malfunction
Front Fog Lamps Malfunction
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.
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.
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, perform the Front Fog Lamps Relay test. The front fog lamps should be ON/OFF.
Circuit/System Testing
1. Ignition OFF, disconnect the appropriate harness connector at the front fog lamps listed below:
* E29LF Fog Lamp - Left Front
* E29RF Fog Lamp - Right Front
2. Test for less than 5 ohm between the appropriate front fog lamp ground circuit harness connector terminal A and ground.
• If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect the harness connector to the fog lamps.
4. Ignition ON, connect a test lamp between fuse F48UA output contact and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
5. Connect a 5 A fused jumper wire between B+ and fuse F48UA output contact.
• If the front fog lamps illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the X50A Fuse Block - Underhood.
• If the front fog lamps do not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the X50A Fuse Block - Underhood.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for BCM replacement, setup and programming