GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference: Lighting Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Place the headlamp switch in the HEADLAMP position.
  2. Place the headlamp dimmer switch in the LOW position.

Do the low beam headlamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Disconnect the lighting relay.
  2. Probe the switch side input circuit of the lighting relay with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 15

4

Connect a fused jumper wire between the switch side input circuit and the switch side output circuit of the lighting relay.

Do the low beam headlamps illuminate?

Go to Step 5

Go to Step 8

5

  1. Disconnect the fused jumper wire.
  2. Probe the coil side voltage supply circuit of the lighting relay with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 16

6

Connect a test lamp between the coil side voltage supply circuit and the coil side control circuit of the lighting relay.

Does the test lamp illuminate?

Go to Step 12

Go to Step 7

7

  1. Connect a fused jumper wire between the coil side voltage supply circuit and the coil side control circuit of the lighting relay.
  2. Place the headlamp switch in the OFF position.
  3. Disconnect the multifunction switch.
  4. Probe the coil side control circuit of the lighting relay at the multifunction switch connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 17

8

  1. Leave the fused jumper wire connected.
  2. Disconnect the lighting high low relay.
  3. Probe the switch side low beam voltage supply circuit of the lighting high low relay with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 18

9

Probe the coil side voltage supply circuit of the lighting high low relay with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 19

10

Connect a test lamp between the coil side voltage supply circuit and the coil side control circuit of the lighting high low relay.

Does the test lamp illuminate?

Go to Step 14

Go to Step 11

11

  1. Connect a fused jumper wire between the coil side voltage supply circuit and the coil side control circuit of the lighting high low relay.
  2. Place the headlamp switch in the OFF position.
  3. Disconnect the multifunction switch.
  4. Probe the coil side control circuit of the lighting high low relay at the multifunction switch connector with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 20

12

Inspect for poor connections at the lighting relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 24

Go to Step 21

13

Inspect for poor connections at the multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 24

Go to Step 22

14

Inspect for poor connections at the lighting high low relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 24

Go to Step 23

15

Repair an open or high resistance in the switch side input circuit of the lighting relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 24

--

16

Repair an open or high resistance in the coil side voltage supply circuit of the lighting relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 24

--

17

Repair an open or high resistance in the coil side control circuit of the lighting relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 24

--

18

Repair an open or high resistance in the switch side low beam voltage supply circuit of the lighting high low relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 24

--

19

Repair an open or high resistance in the coil side voltage supply circuit of the lighting high low relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 24

--

20

Repair an open or high resistance in the coil side control circuit of the lighting high low relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 24

--

21

Replace the lighting relay.

Did you complete the replacement?

Go to Step 24

--

22

Replace the multifunction switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the replacement?

Go to Step 24

--

23

Replace the lighting high low relay.

Did you complete the replacement?

Go to Step 24

--

24

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3