GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

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

Does the scan tool show any DTCs?

--

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

Go to Step 2

2

  1. Turn the headlamp switch to the ON position.
  2. Disconnect the left low beam headlamp.
  3. Connect a test lamp from terminal A to ground.

Does the test lamp light?

--

Go to Step 3

Go to Step 5

3

Connect a self-powered test lamp from terminal B to ground.

Does the test lamp light?

--

Go to Step 6

Go to Step 4

4

Locate and repair the open in CKT 525 (YEL) between the UBEC and the headlamp.

Is the repair complete?

--

System OK

--

5

Locate and repair the open in CKT 1340 (ORN) between the UBEC and the headlamp.

Is the repair complete?

--

System OK

--

6

Replace the headlamp. Refer to Headlamp Bulb Replacement .

Is the repair complete?

--

System OK

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