GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 Seville 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Fog Lamps Inoperative

Test Description

The numbers below refer to the numbers on the diagnostic table

  1. The front fog lamp switch must be placed in the ON position in order to operate the rear fog lamps (w/T79).

    2.

  2. This step verifies whether both front fog lamps, or both rear fog lamps (w/T79) are inoperative.

Step

Action

Yes

No

Schematic Reference: Fog Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System

1

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the front fog lamp switch or the rear fog lamp switch (w/T79) in the ON position.

Do the fog lamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Are both fog lamps inoperative?

Go to Step 4

Go to Step 13

4

Observe the front fog lamp switch parameter or the rear fog lamp switch parameter (w/T79) in the Instrument Panel Integration Module (IPM) Non-HVAC Data list.

Does the scan tool display ON?

Go to Step 7

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the headlamp switch, or the I/P Dimmer/Fog Lamp Switch (w/T79).
  3. Turn ON the ignition with the engine OFF.
  4. Connect a test lamp between the fog lamp switch signal circuit and a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 15

6

Connect a test lamp between the fog lamp switch signal circuit and the ground circuit of the fog lamp switch.

Does the test lamp illuminate?

Go to Step 20

Go to Step 22

7

With a scan tool command the FOG LP relay, or the RR FOG LP relay (w/T79) ON and OFF.

Do you hear a click when you command the fog lamp relay ON and OFF?

Go to Step 10

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the FOG LP relay, or the RR FOG LP relay (w/T79).
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the ignition 1 voltage circuit of the fog lamp relay coil and a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 23

9
  1. Connect a test lamp between the ignition 1 voltage circuit of the fog lamp relay coil and the control circuit of the fog lamp relay.
  2. With a scan tool command the fog lamp relay ON.

Does the test lamp illuminate?

Go to Step 19

Go to Step 16

10
  1. Turn OFF the ignition.
  2. Disconnect the FOG LP relay, or the RR FOG LP relay (w/T79).
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit of the fog lamp relay switch and a good ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 24

11

Connect a 10-amp fused jumper (w/o T79), or a 15-amp fused jumper (w/T79) between the battery positive voltage circuit of the fog lamp relay switch and the supply voltage circuit of the fog lamps.

Do the fog lamps illuminate?

Go to Step 19

Go to Step 12

12
  1. Disconnect the harness connector of the appropriate fog lamp.
  2. Connect a test lamp between the supply voltage circuit of the fog lamp and a good ground.

Does the test lamp illuminate?

Go to Step 25

Go to Step 26

13
  1. Disconnect the harness connector of the inoperative fog lamp.
  2. Connect a test lamp between the supply voltage circuit of the inoperative fog lamp and a good ground.
  3. Place the fog lamp switch in the ON position.

Does the test lamp illuminate?

Go to Step 14

Go to Step 26

14

Connect a test lamp between the supply voltage circuit of the inoperative fog lamp and the ground circuit of the inoperative fog lamp.

Does the test lamp illuminate?

Go to Step 21

Go to Step 25

15

Test the fog lamp switch signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 17

16

Test the control circuit of the fog lamp relay for an open or short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 18

17

Inspect for poor connections at the instrument panel integration module (IPM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 28

18

Inspect for poor connections at the dash integration module (DIM) or the rear integration module (RIM) (w/T79). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 27

19

Inspect for poor connections at the FOG LP relay, or the RR FOG LP relay (w/T79). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 29

20

Inspect for poor connections at the headlamp switch or the I/P dimmer/fog lamp switch (w/T79). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 30

21

Inspect for poor connections at the inoperative fog lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 32

Go to Step 31

22

Repair an open or high resistance in the ground circuit of the fog lamp switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

23

Repair an open or high resistance in the ignition 1 voltage circuit of the fog lamp relay coil. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

24

Repair an open or high resistance in the battery positive voltage circuit of the fog lamp relay switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

25

Repair an open or high resistance in the ground circuit of the fog lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

26

Repair an open or high resistance in the supply voltage circuit of the fog lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 32

--

27

Important:: Perform the setup procedure for the appropriate control module. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the DIM, or the RIM (w/T79). Refer to Dash Integration Module Replacement or Rear Integration Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 32

--

28

Important:: Perform the setup procedure for the IPM. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 32

--

29

Replace the FOG LP relay, or the RR FOG LP relay (w/T79). Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 32

--

30

Replace the headlamp switch or the I/P dimmer/fog lamp switch (w/T79). Refer to Headlamp Switch Replacement or Fog Lamp and Instrument Panel Lamp Dimmer Switch Replacement .

Did you complete the replacement?

Go to Step 32

--

31

Replace the inoperative fog lamp. Refer to Front Fog Lamp Bulb Replacement .

Did you complete the replacement?

Go to Step 32

--

32

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2