GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Lighting Systems Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Verify that the headlamps are inoperative in low light conditions.

Do the headlamps operate normally?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Turn the Headlamp Switch to the HEAD position.

Do the headlamps operate normally?

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Go to Step 4

Go to Headlamps Inoperative - Low Beams

4

Use the Scan Tool to inspect for the following related Body Control Module (BCM) Data/ Input parameters and Output controls.

Refer to Scan Tool Data List in Body Control System for typical values and definitions.

    • Headlamp Ambient Light Sensor
    • Auto Headlamps
    • Headlamp Relay Feedback
    • Daytime Running Lamps Relay
    • Headlamp Power Relay
    • High Beam Switch
    • Flash to Pass Switch

Did you find and correct a problem?

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Go to Step 5

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5

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3