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. With the front fog lamp switch activated the BCM sends a message via serial data to the instrument cluster requesting the instrument cluster to illuminate the front fog indicator.
Reference Information
Schematic Reference
Fog Lights Schematics Fog Lights Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
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 Control Module References for scan tool information
Circuit/System Verification
* Ignition ON, perform the Front Fog Lamps Relay test. The front fog lamps should be ON/OFF.
* Ignition ON, perform the instrument cluster All Indicators test ON and OFF test. The front fog indicator should be ON/OFF.
Circuit/System Testing
Front Fog Lamp Malfunction
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. Disconnect the negative terminal of the C1 Battery.
3. Test for less than 5 ohms between the appropriate front fog lamp ground circuit harness connector terminal 2 and ground.
• If greater than the specified value, test the ground circuit for an open/high resistance.
4. Reconnect the negative terminal to the C1 Battery.
5. Remove the F26UA fuse. Verify that the front fog lamps do not illuminate.
• If any front fog lamp does illuminate, test the signal circuit terminal 31 X1 for a short to voltage.
6. Install a 10 A fused jumper wire between the fuse output contact and B+. Verify that the front fog lamps illuminate.
• If the front fog lamps do not illuminate, test the signal circuit terminal 31 X1 for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate front fog lamp.
7. Disconnect the X2 harness connector at the X50A Fuse Block - Underhood.
8. Connect a test lamp between the signal circuit terminal 19 X2 and B+.
9. Ignition ON, perform the Front Fog Lamps test. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the K9 Body Control Module.
• If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
10. If all circuit test normal, replace the X50A Fuse Block - Underhood.
Front Fog Lamp Switch Malfunction
1. Ignition OFF, disconnect the X1 and X3 at the K9 Body Control Module.
2. Ignition ON, test for less than 0.3 V between the 12 V reference circuit terminal 4 X3 and ground.
• If greater than the specified value, test the 12 V Reference circuit for an short to voltage.
3. Test for less than 0.3 V between the signal circuit terminal 9 X1 and ground.
• If greater than the specified value, test the signal circuit for an short to voltage.
4. Ignition OFF, test for infinite resistance between the signal circuit terminal 9 X1 and ground.
• If less than the specified value, test the signal circuit for an short to ground.
5. Test for infinite resistance between the 12 V reference circuit terminal 4 X3 and ground.
• If less than the specified value, test the 12 V reference circuit for an short to ground.
6. Press and hold the rear fog lamp switch button.
7. Test for 2.7-3.1 kohms between the signal circuit terminal 9 X1 and the 12 V reference circuit terminal 4 X3.
• If not within the specified range, test the 12 V reference circuit and the signal circuit for an open/high resistance. If the circuit test normal replace the S30 Headlamp Switch.
Front Fog Indicator Malfunction
Ignition ON, command the instrument cluster All Indicators test ON and OFF with the scan tool. The front fog indicator lamp should be ON/OFF when changing between the commanded states.
If the front fog indicator stays always on or always off, replace the P16 Instrument Cluster.
If the front fog indicator is changing between ON and OFF, replace the K9 Body Control Module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Front Fog Lamp Replacement Front Fog Lamp Replacement
* Control Module References Control Module References for BCM or instrument panel cluster replacement, setup and programming