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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 and front fog lamps are grounded at all times. When the body control module (BCM) is momentarily grounded when the front fog lamp switch is turned to the ON position. Battery voltage is then supplied to the coil side of the front fog lamp relay. The relay contacts now close supplying the front fog lamps with battery voltage turning them ON.

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

1. Ignition ON, observe the scan tool Front Fog Lamp Switch parameter while turning the fog lamp switch ON and OFF. The parameter should change between Active and Inactive.

• If the parameter does not change between the commanded states, refer to Fog Lamp Switch Malfunction.

2. Command the Front Fog Lamps ON and OFF with a scan tool. The fog lamps should turn ON and OFF when changing between the commanded states.

• If the fog lamps do not change between the commanded states, refer to Fog Lamp Malfunction.

3. Command the Lamp Test ON and OFF with a scan tool. The fog lamps indicator should turn ON and OFF when changing between the commanded states.

• If the front fog lamps indicator illuminates during the test, replace the BCM.
• If the front fog lamps indicator does not illuminate during the test or remains illuminated at all times, replace the instrument cluster.

Circuit/System Testing

Fog Lamp Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition ON, verify the scan tool Front Fog Lamp Switch parameter is Inactive.

• If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the BCM.

3. Install a 3 A fused jumper wire between the signal circuit terminal 7 and the low reference circuit terminal 3. Verify the scan tool Front Fog Lamp Switch parameter is Active.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Fog Lamp Malfunction
1. Ignition OFF, disconnect the X7 harness connector at the fuse block - underhood.
2. Connect a test lamp between the control circuit terminal A7 and ground.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

3. Command the Front Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
4. Ignition OFF, connect the X7 harness connector at the fuse block - underhood. Disconnect the harness connector at the fog lamp - front.
5. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 20 ohm between the ground circuit terminal B and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

6. Connect a test lamp between the control circuit terminal A and ground.
7. Command the Front Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuse block - underhood.
• If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the fuse block - underhood.
• If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the fog lamp - front.

8. If all circuits test normal, test or replace the fog lamp - front

Component Testing

Relay Test
1. Ignition OFF, disconnect the front fog lamp relay.
2. Test for 70-100 ohm between terminals 85 and 86.

• If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

* 30 and 85
* 30 and 86
* 30 and 87
* 85 and 87

• If not the specified value, replace the relay.

4. Install a 10 A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohm between terminals 30 and 87.

• If greater than the specified range, replace the relay.

Fog Lamp Switch Test
1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for infinite resistance between the signal terminal 7 and the low reference terminal 3.

• If not the specified value, replace the headlamp switch.

3. Test for less than 5 ohm between the signal terminal 7 and the low reference terminal 3 while pressing the front fog lamp switch.

• If greater than the specified range, replace the headlamp switch.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Front Fog Lamp Replacement (Canyon) (Removal and Replacement)Front Fog Lamp Replacement (Colorado) (Removal and Replacement)
* Front Fog Lamp Bulb Replacement (Canyon) (Service and Repair)Front Fog Lamp Bulb Replacement (Colorado) (Service and Repair)
* Headlamp Switch Replacement (Service and Repair)
* Underhood Electrical Center or Junction Block Replacement (Removal and Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming

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