GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Venture Ext. 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Headlamp Low or High Beams Always On

Headlamp Low or High Beams Always On Domestic

Step

Action

Value(s)

Yes

No

DEFINITION: The headlamps are on with the headlamp switch OFF and the ignition switch OFF.

1

Was the Lighting System Diagnostic System check performed?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2
  1. Place the ignition switch in the OFF position.
  2. Place the headlamp and IP lamp dimmer switch in the OFF position.
  3. Place the headlamp dimmer switch in the LOW position.
  4. Place the headlamp dimmer switch in the HIGH position.

Do both the low beam headlamps and high beam headlamps illuminate?

--

Go to Step 4

Go to Step 3

3

Do the low beam headlamps illuminate?

--

Go to Step 5

Go to Step 11

4
  1. Disconnect the headlamp and IP lamp dimmer switch.
  2. Place the headlamp dimmer switch in the LOW position.
  3. Place the headlamp dimmer switch in the HIGH position.

Do both the low beam headlamps and high beam headlamps illuminate?

--

Go to Step 10

Go to Step 20

5
  1. Disconnect the underhood accessory wiring junction block connector C2.
  2. Connect a test lamp between terminal F8 of the underhood accessory wiring junction block connector C2 and a good ground.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 7

6

Repair the short to B+ in CKT 12 between the underhood accessory wiring junction block and the headlamp dimmer switch.

Is the repair complete?

--

Go to Step 21

--

7
  1. Connect the underhood accessory wiring junction block connector C2
  2. Disconnect the underhood accessory wiring junction block connector C3

Does either the RH low beam headlamps or LH low beam headlamp illuminate?

--

Go to Step 8

Go to Step 9

8

Repair the short to B+ in CKT 12 between the illuminated headlamp and the underhood accessory wiring junction block.

Is the repair complete?

--

Go to Step 21

--

9

Replace the underhood accessory wiring junction block.

Is the repair complete?

--

Go to Step 21

--

10
  1. Disconnect the daytime running lamps (DRL) control module.
  2. Place the headlamp dimmer switch in the LOW position.
  3. Place the headlamp dimmer switch in the HIGH position.

Do both the low beam headlamps and high beam headlamps illuminate?

--

Go to Step 19

Go to Step 18

11

Disconnect the headlamp dimmer switch

Does the high beam headlamps illuminate?

--

Go to Step 12

Go to Step 17

12
  1. Disconnect the underhood accessory wiring junction block connector C2.
  2. Connect a test lamp between terminal F4 of the underhood accessory wiring junction block connector C2 and a good ground.

Does the test lamp illuminate?

--

Go to Step 13

Go to Step 14

13

Repair the short to B+ in CKT 11 between the underhood accessory wiring junction block and the headlamp dimmer switch.

Is the repair complete?

--

Go to Step 21

--

14
  1. Connect the underhood accessory wiring junction block connector C2
  2. Disconnect the underhood accessory wiring junction block connector C3

Does either the RH high beam headlamps or LH high beam headlamp illuminate?

--

Go to Step 15

Go to Step 16

15

Repair the short to B+ in CKT 11 between the illuminated headlamp and the underhood accessory wiring junction block.

Is the repair complete?

--

Go to Step 21

--

16

Replace the underhood accessory wiring junction block.

Is the repair complete?

--

Go to Step 21

--

17
  1. Locate a short to B+ in CKT 11 between C201 and the headlamp dimmer switch.
  2. If the circuit is OK, replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel Column -Tilt.

Is the repair complete?

--

Go to Step 21

--

18
  1. Test for a short to B+ at terminal F and terminal  C of the daytime running lamp control module.
  2. If the circuits are OK, replace the daytime running lamps (DRL) module.

Did you find and correct the condition?

--

Go to Step 21

--

19

Repair the short to B+ in CKT 10.

Is the repair complete?

--

Go to Step 21

--

20

Replace the headlamp and IP dimmer switch. Refer to Headlamp Switch Replacement .

Is the repair complete?

--

Go to Step 21

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2

Headlamp Low or High Beams Always On Export

Step

Action

Value(s)

Yes

No

1

Was the Lighting System Diagnostic System check performed?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2
  1. Place the ignition switch in the OFF position.
  2. Place the headlamp and IP lamp dimmer switch in the OFF position.
  3. Place the headlamp dimmer switch in the LOW position.
  4. Place the headlamp dimmer switch in the HIGH position.

Do both the low beam headlamps and high beam headlamps illuminate?

--

Go to Step 4

Go to Step 3

3

Do the low beam headlamps illuminate?

--

Go to Step 5

Go to Step 11

4
  1. Disconnect the headlamp and IP lamp dimmer switch.
  2. Place the headlamp dimmer switch in the LOW position.
  3. Place the headlamp dimmer switch in the HIGH position.

Do both the low beam headlamps and high beam headlamps illuminate?

--

Go to Step 10

Go to Step 21

5

Remove the LH Head LP LOW Fuse.

Does the LH low beam headlamps illuminate?

--

Go to Step 6

Go to Step 7

6

Repair the short to B+ in CKT 712 between the fuse block and the LH headlamp.

Is the repair complete?

--

Go to Step 22

--

7

Remove the RH Head LP LOW Fuse.

Does the RH low beam headlamps illuminate?

--

Go to Step 8

Go to Step 9

8

Repair the short to B+ in CKT 312 between the fuse block and the RH headlamp.

Is the repair complete?

--

Go to Step 22

--

9

Repair the short to B+ in CKT 12 between the fuse block and the Headlamp dimmer switch.

Is the repair complete?

--

Go to Step 22

--

10

Is the vehicle equipped with daytime running lamps?

--

Go to Step 18

Go to Step 19

11

Disconnect the headlamp dimmer switch

Does the high beam headlamps illuminate?

--

Go to Step 12

Go to Step 17

12

Remove the LH Head LP HIGH Fuse.

Does the LH high beam headlamps illuminate?

--

Go to Step 13

Go to Step 14

13

Repair the short to B+ in CKT 711 between the fuse block and the LH headlamp.

Is the repair complete?

--

Go to Step 22

--

14

Remove the RH Head LP HIGH Fuse.

Does the RH high beam headlamps illuminate?

--

Go to Step 15

Go to Step 16

15

Repair the short to B+ in CKT 311 between the fuse block and the RH headlamp.

Is the repair complete?

--

Go to Step 22

--

16

Repair the short to B+ in CKT 11 between the fuse block and the Headlamp dimmer switch.

Is the repair complete?

--

Go to Step 22

--

17
  1. Locate a short to B+ in CKT 11 between C201 and the headlamp dimmer switch.
  2. Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel Column -Tilt.

Is the repair complete?

--

Go to Step 22

--

18
  1. Disconnect the Daytime running lamps (DRL) control module .
  2. Place the headlamp dimmer switch in the LOW position.
  3. Place the headlamp dimmer switch in the HIGH position.

Do both the low beam headlamps and high beam headlamps illuminate?

--

Go to Step 19

Go to Step 20

19

Repair the short to B+ in CKT 10 between the fuse block and the Headlamp dimmer switch.

Is the repair complete?

--

Go to Step 22

--

20

Replace the daytime running lamps (DRL) relay.

Is the repair complete?

--

Go to Step 22

--

21

Replace the headlamp and IP dimmer switch. Refer to Headlamp Switch Replacement .

Is the repair complete?

--

Go to Step 22

--

22

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2