For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Fog Lights Schematics Connector End View Reference: Master Electrical Component List
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Are both front fog lamps inoperative? | Go to Step 3 | Go to Step 9
3 |

1. Install the scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the Front Fog Lamp Relay Status parameter in the instrument panel module (IPM) outputs data list.
4. Turn the front fog lamp switch OFF and ON.

Does the scan tool indicate the front fog lamp relay status parameter changes from OFF to ON as the fog lamp switch is activated?

Go to Step 5

Go to Step 4

4 |

1. Turn OFF the ignition.
2. Disconnect the C2 harness connector at the turn signal/multifunction switch.
3. Connect a 3-amp fused jumper between the front fog lamp switch signal circuit and the front fog lamp switch ground circuit.
4. Turn ON the ignition, with the engine OFF.
5. With a scan tool, observe the Front Fog Lamp Relay Status parameter in the IPM outputs data list.

Does the scan tool indicate the front fog lamp relay status parameter is ON?

Go to Step 15

Go to Step 10

5 |

1. Turn OFF the ignition.
2. Disconnect the front fog lamp relay. Refer to Relay Replacement .
3. Turn ON the ignition, with the engine OFF.
4. Probe the front fog lamp relay control side supply voltage circuit with a test lamp connected to ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 20

6 | Probe the front fog lamp relay switch side supply voltage circuit with a test lamp that is connected to ground. Does the test lamp illuminate? | Go to Step 7 | Go to Step 19
7 |

1. Turn OFF the ignition.
2. Connect a test lamp between the front fog lamp relay control side supply voltage circuit and the front fog lamp relay control circuit.
3. Turn ON the ignition, with the engine OFF.
4. Place the front fog lamp switch in the ON position.

Does the test lamp illuminate?

Go to Step 8

Go to Step 13

8 |

1. Turn OFF the ignition.
2. Connect a 15-amp fused jumper between the front fog lamp relay switch side supply voltage circuit and the front fog lamp supply voltage circuit.
3. Turn ON the ignition, with the engine OFF.

Do both front fog lamps illuminate?

Go to Step 14

Go to Step 12

9 |

1. Turn OFF the ignition.
2. Remove the inoperative front fog lamp bulb.
3. Connect a test lamp between the inoperative front fog lamp supply voltage circuit and the inoperative front fog lamp ground circuit.
4. Turn ON the ignition, with the engine OFF.
5. Turn ON the front fog lamp switch.

Does the test lamp illuminate?

Go to Step 17

Go to Step 12

10 | Test the front fog lamp switch ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 11
11 | Test the front fog lamp switch signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 16
12 | Test the front fog lamp supply voltage circuit for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 18
13 | Test the front fog lamp relay control circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 16
14 | Inspect for poor connections at the front fog lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 21
15 | Inspect for poor connections at the harness connector of the turn signal/multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 22
16 | Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 23
17 | Inspect for poor connections at the inoperative front fog lamp bulb. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 25 | Go to Step 24
18 | Locate and repair an open or high resistance in the front fog lamp ground circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | Go to Step 25 | --
19 | Locate and repair an open or high resistance in the switch side supply voltage circuit of the front fog lamp relay. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 25 | --
20 | Locate and repair an open or high resistance in the control side supply voltage circuit of the front fog lamp relay. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | Go to Step 25 | --
21 | Replace the front fog lamp relay. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 25 | --
22 | Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement . Did you complete the replacement? | Go to Step 25 | --
23 | Replace the IPM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 25 | --
24 | Replace the inoperative front fog lamp bulb. Refer to Front Parking and Turn Signal and Fog Lamp Assembly Replacement . Did you complete the replacement? | Go to Step 25 | --
25 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2