For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Fog Lights Schematics . Connector End View Reference: Component Connector End Views , or Master Electrical Component List
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Verify the front fog lamps are inoperative. Do the front fog lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3
3 | Is only one front fog lamp inoperative? | Go to Step 4 | Go to Step 6
4 | Inspect the inoperative bulb and socket for an open filament or poor terminal contact and repair or replace as necessary. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | System OK | Go to Step 5
5 | Test the ground circuit of the inoperative lamp for a high resistance or an open. Did you find and correct the condition? | System OK | Repair the fog lamp supply circuit of the inoperative lamp. Refer to Wiring Repairs .
6 | Engine OFF, turn the key to RUN and the headlamp switch to PARK. Do the courtesy lamps illuminate? | Go to Step 7 | Go to Courtesy Lamps Inoperative
7 | Inspect the fog lamp fuse. Is the fuse open? | Repair the fog lamp supply circuit of the inoperative lamp for a short to ground. Refer to Wiring Repairs . | Go to Step 8
8 |

1. Place the front fog lamp switch in the ON position.
2. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block connector. Refer to Circuit Testing and Wiring Repairs .

Was a ground signal present?

Go to Step 11

Go to Step 9

9 | Test the front fog lamp switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | System OK | Go to Step 10
10 |

1. Remove the fog lamp switch.
2. Place a fused jumper between the fog lamp switch signal and ground connector terminals.
3. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing and Wiring Repairs .

Was a ground signal present?

Replace the front fog lamp switch. Refer to Headlamp Switch Replacement .

Go to Step 12

11 | Test for an open or high resistance in the front fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | System OK | Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement .
12 | Test the fog lamp relay control circuit for an open high resistance or a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | System OK | Go to Step 13
13 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | System OK | Replace the BCM. Refer to Control Module References , for replacement, setup, and programming.