GM Service Manual Online
For 1990-2009 cars only

Headlamps Inoperative - Low Beams Domestic

Step

Action

Yes

No

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

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

DEFINITION: The low beam headlamps are inoperative, high beam headlamps operate properly.

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. Place the ignition switch in the OFF position.
  2. Turn the headlamp switch to the HEAD position.
  3. 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 6

4

Using a test lamp connected to ground, probe between the headlamp low beam supply voltage circuit of connector C201.

Does the test lamp illuminate?

Go to Step 5

Go to Step 9

5

Using a test lamp connected to ground, probe between the headlamp low beam supply voltage circuit of the underhood junction block connector.

Does the test lamp illuminate?

Go to Step 10

Go to Step 11

6

Using a test lamp connected to ground, probe the supply voltage circuit of the inoperative low beam headlamp.

Does the test lamp illuminate?

Go to Step 8

Go to Step 7

7

Test for an open or high resistance in the 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 10

8

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 15

Go to Step 12

9

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 15

Go to Step 13

10

Inspect for poor connections at the harness connector of the underhood junction 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, high resistance or short to ground in the low beam supply voltage circuit of the underhood junction 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 turn signal switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the repair?

Go to Step 15

--

14

Replace the underhood junction 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

Headlamps Inoperative - Low Beams Export

Step

Action

Yes

No

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

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

DEFINITION: The low beam headlamps are inoperative, high beam headlamps operate properly.

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. Place the ignition switch in the OFF position.
  2. Place the headlamp switch in the HEAD position.
  3. Place the headlamp dimmer switch in 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 5

Go to Step 4

4

Inspect the corresponding fuse of the inoperative low beam headlamp for an open.

Is the RH or LH HEAD LP LOW fuse open?

Go to Step 11

Go to Step 6

5

Using a test lamp connected to ground, probe the headlamp low beam supply voltage circuit of connector C201.

Does the test lamp illuminate?

Go to Step 10

Go to Step 8

6

Using a test lamp connected to ground, probe the low beam supply voltage circuit of the inoperative headlamp.

Does the test lamp illuminate?

Go to Step 7

Go to Step 9

7

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 14

Go to Step 12

8

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 14

Go to Step 13

9

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

Did you complete the repair?

Go to Step 14

--

10

Repair an open or high resistance in the low beam 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 14

--

11

Repair a short to ground in the low beam supply voltage circuit of the inoperative headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

12

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

Did you complete the repair?

Go to Step 14

--

13

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 14

--

14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2