GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

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

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Turn the headlamp switch to the OFF position.

Do the low and high beam headlamps remain OFF?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Remove the appropriate component either the headlamp module for low beams or HI BEAM relay for high beams.

Do the lamps turn OFF?

Go to Step 5

Go to Step 4

4

Repair a short to battery positive voltage in the supply circuit of the affected headlamps. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 13

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5

  1. Reinstall the appropriate component.
  2. Disconnect the lamp switch assembly.

Do the headlamps turn OFF?

Go to Step 12

Go to Step 6

6

Are the high beam headlamps on at all times?

Go to Step 7

Go to Step 8

7

Test for a short to ground in FTP circuit and the headlamp dimmer switch high beam signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

Test for a short to ground in the headlamp switch ON signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 9

9

Disconnect the body control module (BCM) connector C1.

Do the headlamps turn OFF?

Go to Step 14

Go to Step 10

10

Test for a short to ground in the affected low or high beam relay control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 11

11

Replace the appropriate headlamp module or HI BEAM relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 14

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12

Replace the lamp switch assembly. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 14

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13

Replace the BCM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3