GM Service Manual Online
For 1990-2009 cars only

Fog Lamps Inoperative - All Front

Step

Action

Value(s)

Yes

No

1

Inspect fuse H5-H6.

Is the fuse open?

--

Go to Step 2

Go to Step 3

2

Repair the short to ground in circuit 9.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

3

Inspect fuse 27.

Is the fuse open?

--

Go to Step 14

Go to Step 4

4

Inspect for any diagnostic trouble codes (DTCs).

Are any DTCs present?

--

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 5

5

  1. Turn the ignition switch to the RUN position.
  2. Turn the fog lamp switch to the ON position.
  3. Turn the headlamp dimmer switch to the LOW position.
  4. Using a test light, backprobe between the fog lamp switch harness connector terminal 7 and ground.

Does the test light illuminate?

--

Go to Step 6

Go to Step 13

6

Using a test light, backprobe between the fog lamp switch harness connector terminal 7 and terminal 4.

Does the test light illuminate?

--

Go to Step 7

Go to Step 8

7

Replace the front fog lamp switch. Refer to Fog Lamp Switch Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

8

Using a test light, backprobe the underhood accessory wiring junction block harness connector C2 terminal E6 to ground.

Is the test light on?

--

Go to Step 11

Go to Step 10

9

Repair a poor connection or an open in circuit 451 between the underhood accessory junction block harness connector C1 terminal C1 and G113.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

10

Repair the poor connection or the open in circuit 1317.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

11

Replace relay 16.

Do the fog lamps turn on?

--

Go to Diagnostic System Check - Lighting Systems

Go to Step 12

12

Using a test light, backprobe the underhood accessory wiring junction block harness connector C2 terminal E6 to connector C1 terminal C1.

Does the test light illuminate?

--

Go to Step 15

Go to Step 9

13

Repair a poor connection or an open in circuit 9 between the fuse block terminal H6 and electronic traction control and fog lamp switch assembly harness connector C2 terminal 7.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

14

Replace the underhood accessory wiring junction block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

15

Using a test light, backprobe the underhood accessory wiring junction block harness connector C3 terminal A6 to ground.

Is the test light on?

--

Go to Step 16

Go to Step 14

16

Repair a poor connection or an open in circuit 1350 between S124 and G101.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

Fog Lamps Inoperative - All Rear

Step

Action

Value(s)

Yes

No

1

Inspect fuse F3-F4.

Is the fuse open?

--

Go to Step 2

Go to Step 3

2

Repair the short to ground in circuit 1840.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

3

Inspect for any diagnostic trouble codes (DTCs).

Are any DTCs present?

--

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 4

4

  1. Turn the ignition switch to the RUN position.
  2. Using a test light, backprobe the rear fog lamp relay connector terminal C2 to ground and then C1 to ground.

Does the test light illuminate in both places?

--

Go to Step 11

Go to Step 8

5

Using a test light, backprobe between the body control module harness connector C1 terminal C8 to ground.

Does the test light illuminate?

--

Go to Step 6

Go to Step 10

6

Using a DMM, test for continuity in circuit 1977 between the electronic traction control switch and fog lamp switch assembly harness connector C2 terminal 6 and the body control module harness connector C2 terminal A8.

Is the there continuity in the circuit?

--

Go to Step 7

Go to Step 13

7

  1. Disconnect C2 on the electronic traction control switch and fog lamp switch assembly.
  2. Press the rear fog lamp switch to the ON position
  3. Using a DMM, test for continuity between the electronic traction control switch and fog lamp switch assembly connector C2 terminal 6 and terminal 4.

Is there continuity?

--

Go to Step 12

Go to Step 9

8

Repair a poor connection or an open in circuit 1840 between S215 and the rear fog lamp relay.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

9

Replace the rear fog lamp switch. Refer to Rear Fog Lamp Switch Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

10

Repair a poor connection or an open in circuit 1317.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

11

Replace the rear fog lamp relay.

Do the rear fog lamps turn on?

--

Go to Diagnostic System Check - Lighting Systems

Go to Step 5

12

Using a test light, backprobe B+ and the electronic traction control switch and fog lamp switch assembly harness connector C2 terminal 4.

Does the test light illuminate?

--

Go to Step 14

Go to Step 15

13

Repair a poor connection or an open in circuit 1977.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

14

Using a test light, backprobe between C915 terminal D to ground.

Does the test light illuminate?

--

Go to Step 16

Go to Step 17

15

Repair a poor connection or an open in circuit 1550 between electronic traction control switch and fog lamp switch assembly harness connector C2 terminal D and G203.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

16

Repair a poor connection or an open in circuit 350 between S930 and G402.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--

17

Repair a poor connection or an open in circuit 122 between the rear fog lamp relay terminal A2 and C915 terminal D.

Is the repair complete?

--

Go to Diagnostic System Check - Lighting Systems

--