GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Did you review the Headlights/Daytime Running Lights (DRL) Circuit Description and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Lighting Systems

2

  1. Start the engine.
  2. Turn the headlamp switch to head and OFF while observing the headlamps.

Did the headlamp illuminate at full intensity and dim back to DRL mode?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the ambient light sensor connector.
  3. Start the engine.
  4. Operate the headlamps as described in the last step.

Do the headlamps and the DRL operate normally?

Go to Step 4

Go to Step 5

4

Replace the ambient light sensor. Refer to Daytime Running Lamp (DRL) Ambient Light Sensor Replacement .

Did you complete the repair?

Go to Step 6

--

5

Replace the DRL control module. Refer to Daytime Running Lights (DRL) Control Module Replacement .

Did you complete the repair?

Go to Step 6

--

6

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3