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: Lighting Systems Connector End Views or Data Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Ensure the park brake is released.
  2. Turn ON the ignition, with the engine OFF.
  3. With the brake pedal depressed, place the gear selector in any drive gear.
  4. Place the headlamps in the ON position.

Does the system operate normally?

Go to Testing for Electrical Intermittents

Go to Step 3

3

  1. Place the headlamps in the AUTO position.
  2. Disconnect the daytime running lamps (DRL) relay.

Do the DRL turn OFF?

Go to Step 4

Go to Step 7

4

  1. Reconnect the DRL relay.
  2. Use the scan tool to observe the DRL parameter and command the DRL ON and OFF several times.

Does the DRL parameter change states as expected?

Go to Step 5

Go to Step 6

5

Inspect for poor connections at the harness connector of the DRL relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

6

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

7

Repair the DRL supply voltage circuit. Refer to Wiring Repairs.

Did you complete the repair?

Go to Step 10

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8

Replace the DRL relay. Refer to Relay Replacement.

Did you complete the replacement?

Go to Step 10

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9

Replace the BCM. Refer to Control Module References.

Did you complete the replacement?

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3