GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Turn the ignition to the ON position.
  2. Ensure the park brake is set.
  3. Connect a scan tool.
  4. Using the scan tool, check for any DTCs in the body control module (BCM).

Does the scan tool show any DTCs?

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Go to Diagnostic System Check - Body Control System in Body Control System

Go to Step 2

2

  1. Turn the headlamp switch to the AUTO position.
  2. Cover the ambient light sensor in order to block out all light.

Do the the headlights light and the daylight running lamps (DRL) turns off?

--

System OK

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the BCM.
  3. Remove the DRL relay.
  4. Using a J 39200 DMM and J 35616 adaptor, measure the resistance from terminal 85 of the DRL relay to ground.

Is the resistance greater than the specified value?

1M ohms

Go to Step 5

Go to Step 4

4

Locate and repair CKT 592 (LT GRN/BLK) for a short to ground.

Is the repair complete?

--

System OK

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5

Using a J 39200 DMM, measure the resistance from terminal 30 to terminal 87 of the DRL relay.

Is the resistance greater than the specified value?

1M ohms

Go to Step 7

Go to Step 6

6

Replace the DRL relay. Refer to Daytime Running Lamps (DRL) Relay Replacement .

Is the repair complete?

--

System OK

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7

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Is the repair complete?

--

System OK

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