GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Turn the headlamps dimmer switch to the HI position and observe the headlamps.

Did the highbeam filaments light?

--

Go to Step 2

Go to Step 5

2

  1. Turn the headlamps dimmer switch to the LOW position.
  2. Remove the daytime running light (DRL) relay.
  3. Connect a test lamp between terminal D4 in the daytime running light relay socket and chassis ground.

Did the test lamp light?

--

Go to Step 3

Go to Step 4

3

  1. Disconnect the right headlamp harness connector.
  2. Connect a fused jumper wire between terminal C in the right headlamp harness connector and chassis ground.
  3. Use a DMM between terminal D3 in the DRL Relay socket and chassis ground.

Does the DMM indicate continuity?

--

Go to Step 9

Go to Step 10

4

  1. Turn the headlamps dimmer switch to the LOW position.
  2. Disconnect the headlamps dimmer switch harness connector.
  3. Use a DMM between terminal C and terminal D in the headlamps dimmer switch connector.

Does the DMM indicate continuity?

--

Go to Step 11

Go to Step 12

5

Inspect the DRL for proper operation.

Does the DRL operate properly?

--

Go to Step 6

Go to Step 7

6

  1. Disconnect the headlamps dimmer switch harness connector.
  2. Disconnect the headlamp switch harness connector.
  3. Use a DMM between terminal D in the headlamp switch harness connector and terminal D in the headlamp dimmer switch harness connector.

Does the DMM indicate continuity?

--

Go to Step 13

Go to Step 14

7

  1. Disconnect the headlamp switch harness connector.
  2. Connect a test lamp between terminal C in the headlamp switch harness connector and chassis ground.

Did the test lamp light?

--

Go to Step 8

Go to Step 15

8

Use a DMM between terminal B and terminal C in the headlamp switch.

Does the DMM indicate continuity?

--

Go to Step 16

Go to Step 14

9

Replace the daytime running light relay. Refer to Daytime Running Lamps (DRL) Relay Replacement .

Is the repair complete?

--

System OK

--

10

Locate and repair the open in CKT 12 (TAN) between terminal D3 in the daytime running light relay socket and terminal C in the right headlamp harness connector.

Is the repair complete?

--

System OK

--

11

Locate and repair the open in CKT 544 (PPL) between terminal C in the headlamp dimmer switch harness connector and terminal D4 in the DRL relay socket.

Is the repair complete?

--

System OK

--

12

Replace the headlamps dimmer switch.

Is the repair complete?

--

System OK

--

13

Locate and repair the open in CKT 10 (YEL) between terminal D in the headlamp switch harness connector and terminal D in the headlamps dimmer switch harness connector.

Is the repair complete?

--

System OK

--

14

Replace the headlamp switch.

Is the repair complete?

--

System OK

--

15

Locate and repair the open in CKT 742 (RED) between terminal C in the headlamp switch harness connector and terminal A4 at the HDLP SW Fuse.

Is the repair complete?

--

System OK

--

16

Locate and repair the open in CKT 150 (BLK) between S105 and G101 (Diesel) or G102 (Gasoline).

Is the repair complete?

--

System OK

--