GM Service Manual Online
For 1990-2009 cars only

Headlamp Low or High Beams Always On Japan, Europe

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the OFF position.
  2. Turn the headlamps off.

Do the headlamps remain off?

--

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

Go to Step 3

3

  1. Turn the headlamps off.
  2. Turn the headlamp dimmer switch to the low beam position and then to the high beam position.

Are the headlamps on in both cases?

--

Go to Step 4

Go to Step 5

4

Inspect for and repair a short to battery voltage in the signal circuit of the headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and repair a short?

--

Go to Step 9

Go to Step 6

5

Repair a short to battery voltage in the supply voltage circuit of the low beam headlamps or the supply voltage circuit of the high beam headlamps. Refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 9

--

6

Connect a test lamp between the headlamp switch terminal E and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 8

7

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

--

Go to Step 9

--

8

Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle and Dimmer Switch Assembly - Assemble - Off Vehicle .

Did you complete the replacement?

--

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3

Headlamp Low or High Beams Always On Scandinavia

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the OFF position.
  2. Turn the headlamps off.

Do the headlamps remain off?

--

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

Go to Step 3

3

Are the high beams on at all times?

--

Go to Step 4

Go to Step 5

4

  1. Turn the headlamps off.
  2. Turn the headlamp dimmer switch from the low beam position to the high beam position and then from the high beam position to the low beam position.

Do the headlights illuminate in both cases?

--

Go to Step 7

Go to Step 6

5

  1. Turn the ignition switch to the OFF position.
  2. Turn the headlamps off.
  3. Turn the headlamp dimmer switch from the low beam position to the high beam position and then from the high beam position to the low beam position.

Do the headlamps illuminate in both cases?

--

Go to Step 7

Go to Step 8

6

Repair a short to battery voltage in the supply voltage circuit of the headlamp high beams. Refer to Wiring Repairs in Wiring Repairs.

Did you complete the repair?

--

Go to Step 13

--

7

Inspect for and repair a short to battery voltage in the signal circuit of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and repair a short to battery voltage?

--

Go to Step 13

Go to Step 9

8

Inspect for and repair a short to battery voltage in the supply voltage circuit of the headlamp low beams. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is a short present?

--

Go to Step 13

Go to Step 10

9

Connect a test lamp between the headlamp switch terminal E and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 12

10

Replace the DRL relay.

Did you complete the replacement?

--

Go to Step 13

--

11

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle Dimmer Switch Assembly - Assemble - Off Vehicle .

Did you complete the replacement?

--

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3

Headlamp Low or High Beams Always On Pontiac

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the OFF position.
  2. Turn the headlamps off.

Do the headlamps remain off?

--

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

Go to Step 3

3

Are the high beam headlamps on?

--

Go to Step 4

Go to Step 5

4

Disconnect the headlamp dimmer switch.

Do the high beam headlamps turn off?

--

Go to Step 6

Go to Step 7

5

Disconnect the headlamp switch.

Do the low beam headlamps turn off?

--

Go to Step 8

Go to Step 9

6

Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle and Dimmer Switch Assembly - Assemble - Off Vehicle .

Did you complete the replacement?

--

Go to Step 12

--

7

Repair a short to battery voltage in the supply voltage circuit of the headlamp high beams. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 12

--

8

Replace the headlamp switch. Refer to Headlamp Switch Replacement

Did you complete the replacement?

--

Go to Step 12

--

9

Disconnect the DRL module.

Do the low beam headlamps turn off?

--

Go to Step 10

Go to Step 11

10

Replace the DRL module. Refer to Daytime Running Lights (DRL) Control Module Replacement .

Did you complete the replacement?

--

Go to Step 12

--

11

Repair a short to battery voltage in the signal circuit of the headlamp switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 12

--

12

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3

Headlamp Low or High Beams Always On Chevrolet Domestic, Gulf States

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the OFF position.
  2. Turn the headlamps off.

Do the headlamps remain off?

--

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

Go to Step 3

3

  1. Make sure that the DRL ambient light sensor is not covered.
  2. Turn the headlamps off.
  3. Turn the headlamp dimmer switch to the low beam position and then to the high beam position.

Do the headlamps illuminate in both cases?

--

Go to Step 4

Go to Step 5

4

Disconnect the headlamp switch.

Are the high beam headlamps on?

--

Go to Step 6

Go to Step 7

5

Repair a short to battery voltage in the supply voltage circuit of the low beam headlamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

6

Disconnect the DRL ambient light sensor.

Are the high beam headlamps on?

--

Go to Step 8

Go to Step 9

7

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

--

Go to Step 16

--

8

Inspect for a short to battery voltage and a short to ground in the signal circuit of the ambient light sensor and the low reference signal circuit of the ambient light sensor. Refer to Circuit Testing in Wiring Systems.

Is a short present?

--

Go to Step 10

Go to Step 11

9

Replace the DRL ambient light sensor. Refer to Daytime Running Lamp (DRL) Ambient Light Sensor Replacement .

Did you complete the replacement?

--

Go to Step 16

--

10

Repair a short in the daytime running lamp photocell signal circuit or the daytime running lamp photocell return circuit. Refer to Wiring Repairs in Wiring System

Did you complete the repair?

--

Go to Step 16

--

11

Disconnect the DRL module.

Are the high beam headlamps on?

--

Go to Step 12

Go to Step 13

12

Inspect for a short to battery voltage in the signal circuit of the headlamp switch. Refer to Circuit Testing in Wiring Systems.

Is a short present?

--

Go to Step 14

Go to Step 15

13

Replace the DRL module. Refer to Daytime Running Lights (DRL) Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

14

Repair a short to battery voltage in the signal circuit of the headlamp switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

15

Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle and Dimmer Switch Assembly - Assemble - Off Vehicle .

Did you complete the replacement?

--

Go to Step 16

--

16

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3