For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.
1 |

1. Inspect the body control module (BCM) for DTCs. Refer to Diagnostic Trouble Code (DTC) List/Type in Body Control System.
2. Correct any of the current DTCs before preceding with this diagnosis.

Are all of the code setting conditions corrected?

--

Go to Step 2

Go to Step 3

2 |

1. Connect a Scan Tool to the data link connector (DLC).
2. Turn the headlamp switch to the PARK position.
3. Use the Scan Tool in order to command the fog lamps ON.

Do the fog lamps light?

--

Go to Step 4

Go to Step 5

3 | Correct all code setting conditions that exist. Is the repair complete? | -- | Go to Step 1 | --
4 | Backprobe the BCM connector C3 using a fused jumper between terminal A4 and ground. Is the fog lamp ON input received by the scan tool? | -- | Go to Step 6 | Go to Step 7
5 |

1. Exchange the fog lamp relay with a known good relay from the right IP junction block.
2. Use the Scan Tool in order to command the fog lamps ON.

Do the fog lamps light?

--

Go to Step 8

Go to Step 9

6 |

1. Disconnect the fog lamp switch connector.
2. Connect a fused jumper between terminal A of the fog lamp switch connector and ground.

Is the fog lamp ON input received by the scan tool?

--

Go to Step 10

Go to Step 11

7 | Replace the BCM. Refer to Body Control Module Replacement in Body Control Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
8 | Replace the faulty relay. Is the repair complete? | -- | Go to Exterior Lights System Check | --
9 |

1. Use a test lamp connected to ground in order to backprobe the right IP junction block connector C1 terminal F4.
2. Use the Scan Tool in order to command the fog lamps ON.

Does the test lamp light?

--

Go to Step 15

Go to Step 14

10 | Connect a fused jumper between terminal A and terminal B of the fog lamp switch connector. Is the fog lamp ON input received by the scan tool? | -- | Go to Step 12 | Go to Step 13
11 | Repair the open in CKT 192 between the BFC and the fog lamp switch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
12 | Replace the fog lamp switch. Is the repair complete? | -- | Go to Exterior Lights System Check | --
13 | Repair the open in CKT 251 between the fog lamp switch and the ground splice pack G204. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Exterior Lights System Check | --
14 | Replace the right IP junction block. Is the repair complete? | -- | Go to Exterior Lights System Check | --
15 | Test CKT 34 for an open or short to ground between the right IP junction block and the underhood junction block. Was a condition found and corrected? | -- | Go to Exterior Lights System Check | Go to Step 16
16 | Use a DMM in order to measure the resistance between connector C3 terminal A5 and connector C2 terminal F4 of the underhood junction block. Is the measured resistance within the specified range? | 0-2 ohms | Go to Step 17 | Go to Step 18
17 |

1. Disconnect either fog lamp connector.
2. Use a test lamp connected to battery positive in order to probe terminal B of the fog lamp connector.

Does the test lamp light?

--

Go to Step 19

Go to Step 20

18 | Replace the underhood junction block. Is the repair complete? | -- | Go to Exterior Lights System Check | --
19 | Replace the inoperative fog lamps or fog lamp connectors. Is the repair complete? | -- | Go to Exterior Lights System Check | --
20 | Repair the open in CKT 1350 between the fog lamps and ground splice pack G101. Is the repair complete? | -- | Go to Exterior Lights System Check | --