GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Blazer - 4WD - RHD 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Rear Fog Lamps Inoperative

Step

Action

Value(s)

Yes

No

1

Was the Fog Lights System Check performed?

--

Go to Step 2

Refer to Fog Lights System Check

2
  1. Turn the ignition switch to the ON position. Do not start the vehicle.
  2. Connect the scan tool.
  3. Inspect the system for DTCs in the body control module (BCM).

Does the scan tool show any DTCs?

--

Refer to Diagnostic System Check - Body Control System in Body Control System

Go to Step 3

3

Turn park lamps ON.

Do the park lamps light?

--

Go to Step 4

Refer to Exterior Lights System Check

4
  1. Turn the rear fog lamp switch to the ON position.
  2. Use the scan tool in order to read the switch status in the BCM. Refer to Scan Tool Data List in Body Control System.

Does the scan tool indicate that the switch is closed?

--

Go to Step 9

Go to Step 5

5
  1. Disconnect the rear fog lamp switch.
  2. Connect a fused jumper wire between terminal A and terminal B of the rear fog lamp switch.
  3. Use the scan tool in order to read the switch status in the BCM.

Does the scan tool show that the switch is closed?

--

Go to Step  6

Go to Step 7

6

Replace the rear fog lamp switch.

Is the repair complete?

--

Refer to Fog Lights System Check

--

7
  1. Connect a fused jumper wire between terminal A of the rear fog lamp switch to ground.
  2. Use the scan tool to in order to read the switch status in the BCM.

Does the scan tool show that the switch is closed?

--

Go to Step 8

Go to Step 11

8

Locate and repair the open in CKT 1850 (BLK) between the rear fog lamp switch and ground.

Is the repair complete?

--

Refer to Fog Lights System Check

--

9

Connect a test lamp between CKT 34 (PPL) connector C1 terminal B4 of the underhood fuse block to ground.

Does the test lamp light?

--

Go to Step 14

Go to Step 10

10

Replace the rear fog lamp relay.

Is the repair complete?

--

Refer to Fog Lights System Check

--

11
  1. Remove the jumper wire.
  2. Turn the park lamps OFF.
  3. Turn the ignition switch to the OFF position.
  4. Disconnect the BCM.
  5. Use a J 39200 (DMM) in order to inspect the continuity of CKT 187 (LT BLU) between terminal A of the rear fog lamp switch and connector C3 terminal B7 of the BCM.

Is continuity present?

--

Go to Step 12

Go to Step 13

12

Replace the BCM.

Is the repair complete?

--

Refer to Fog Lights System Check

--

13

Locate and repair the open in CKT 187 (LT BLU) between the switch and the BCM.

Is the repair complete?

--

Refer to Fog Lights System Check

--

14

Locate and repair the open in the following circuits:

    • CKT 34 (PPL) attached to the rear fog lamps.
    • CKT 1350 (BLK) between the rear fog lamps and ground G450.

Is the repair complete?

--

Refer to Fog Lights System Check

--