GM Service Manual Online
For 1990-2009 cars only

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

Connector End View Reference: Master Electrical Component List in Wiring Systems.

DEFINITION: One of the following conditions exist:

    • All the headlamps are inoperative.
    • The LH high beam and LH low beam are inoperative.
    • The RH high beam and RH low beam are inoperative.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn the ignition switch to the OFF position.
  2. Turn the headlamp switch to the HEAD position.
  3. Place the headlamp dimmer switch in the LOW position.
  4. Place the headlamp dimmer switch in the HIGH position.

Do the all headlamps operate properly?

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

Go to Step 3

3

Are all the headlamps inoperative?

Go to Step 4

Go to Step 7

4

  1. Disconnect the headlamp switch connector.
  2. Using a test lamp that is connected to ground, probe the battery positive voltage circuit of the headlamp switch connector that is supplied by the HEADLAMP circuit breaker.

Does the test lamp illuminate?

Go to Step 5

Go to Step 8

5

Connect a fused jumper between the battery positive voltage circuit and the headlamp supply voltage circuit of the headlamp switch connector. Refer to Circuit Testing in Wiring Systems.

Do the headlamps illuminate?

Go to Step 11

Go to Step 6

6

  1. Leave the fused jumper connected.
  2. Using a test lamp connected to ground, probe the headlamp supply voltage circuit of connector C201.

Does the test lamp illuminate?

Go to Step 10

Go to Step 13

7

  1. Disconnect the inoperative headlamp.
  2. Using a test lamp connected to ground, probe the ground circuit of the inoperative headlamp.

Does the test lamp illuminate?

Go to Step 9

Go to Step 12

8

Test for an open or high resistance in the battery positive voltage circuit of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 14

9

Inspect for poor connections at the harness connector 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 18

Go to Step 15

10

Inspect for poor connections at the harness connector of the turn signal 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 18

Go to Step 16

11

Inspect for poor connections at the harness connector of 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 18

Go to Step 17

12

Repair an open or high resistance in the ground circuit of the inoperative headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

13

Repair an open or high resistance in the headlamp supply voltage circuit of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

14

Repair a short to ground in the one of the following circuits:

    • The battery positive voltage circuit
    • The headlamp supply voltage circuit
    • The high beam voltage supply circuit
    • The low beam voltage supply circuit

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 18

--

15

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

Did you complete the repair?

Go to Step 18

--

16

Replace the turn signal switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the repair?

Go to Step 18

--

17

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2