GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Headlights Schematics

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Operate the headlamps to verify the fault is present.

Does the headlamp system operate normally?

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

Go to Step 3

3

Is only one high or low beam inoperative?

Go to Step 4

Go to Step 5

4

Test the power and ground circuits for a poor connection or an open at the inoperative lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Circuit Testing in Wiring Systems.

Did you find a poor connection or an open?

Go to Step 15

Go to Step 11

5

While turning the headlamp switch ON and OFF, listen for an audible click from the headlamp relay.

Does the headlamp relay click?

Go to Step 10

Go to Step 6

6

  1. Remove the headlamp relay.
  2. Turn ON the headlamp switch.
  3. Connect a test lamp between the headlamp relay coil supply voltage circuit of the headlamp relay connector and a good ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 7

7

  1. Disconnect the headlamp switch.
  2. Connect a test lamp between the battery positive voltage circuit of the headlamp switch and a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 16

8

Connect a test lamp between the ground circuit of the headlamp relay and a battery positive voltage circuit.

Does the test lamp illuminate?

Go to Step 14

Go to Step 17

9

Test the relay coil supply voltage circuit for an open or high resistance. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 23

Go to Step 13

10

Connect a test lamp between the ground circuit of the headlamp dimmer switch and a battery positive voltage circuit.

Does the test lamp illuminate?

Go to Step 12

Go to Step 18

11

Inspect for poor connections to the headlamp or bulb. 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 23

Go to Step 19

12

Inspect for poor connections to the multifunction switch. 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 23

Go to Step 20

13

Inspect for poor connections to the headlamp switch. 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 23

Go to Step 21

14

Inspect for poor connections to the headlamp relay. 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 23

Go to Step 22

15

Repair the poor connection or open in the inoperative lamp circuitry. Refer to Connector Repairs or Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

16

Repair the open in the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

17

Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

18

Repair the open in the ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

19

Replace the headlamp. Refer to Headlamp Assembly or Headlamp Bulb Replacement .

Did you complete the replacement?

Go to Step 23

--

20

Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column-Tilt or Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column-Standard.

Did you complete the replacement?

Go to Step 23

--

21

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 23

--

22

Replace the headlamp relay.

Did you complete the replacement?

Go to Step 22

--

23

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2