GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

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

1

Did you perform the Lighting System Diagnostic Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the headlamp switch to the HEAD position.
  2. Turn the headlamp dimmer switch to the LOW position.

Do the low beam headlamps operate properly?

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

Go to Step 3

3

Are both low beam headlamps inoperative

Go to Step 4

Go to Step 7

4

Backprobe between the headlamp low beam supply voltage circuit of connector C201 and a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 6

5

Backprobe between the headlamp low beam supply voltage circuit of the underhood accessory wiring junction block connector C2 and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 11

6

Test for an open or high resistance in the headlamp low beam supply voltage circuit between the headlamp dimmer switch and C201. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 9

7

Test for an open or high resistance in the headlamp low beam supply voltage circuit of the inoperative low beam headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 8

8

Inspect for a poor connection at the harness connection of the inoperative headlamp. 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 15

Go to Step 12

9

Inspect for a poor connection at the harness connection of the headlamp dimmer 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 15

Go to Step 13

10

Inspect for a poor connection at the harness connection of the underhood fuse block. 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 15

Go to Step 14

11

Repair an open or high resistance in the low beam supply voltage circuit between C201 and the underhood fuse block. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 15

--

12

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

Did you complete the repair?

Go to Step 15

--

13

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

Did you complete the repair?

Go to Step 15

--

14

Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems.

Did you complete the repair?

Go to Step 15

--

15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2