GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1

Inspect the body control module (BCM) for any stored DTCs. Refer to Diagnostic Trouble Code (DTC) List/Type in Body Control System.

Does the BCM have any stored DTCs?

--

Go to Step 2

Go to Step 3

2

Correct any code setting conditions that exist. Refer to Diagnostic Trouble Code (DTC) List/Type in Body Control System.

Is the repair complete?

--

Go to Daytime Running Lights (DRL) System Check

--

3

  1. Connect the Scan Tool to the data link connector (DLC).
  2. Command the automatic lamp control to ON.

Do the park lamps light?

--

Go to Step 4

Go to Step 5

4

Replace the ambient light sensor.

Is the repair complete?

--

Go to Daytime Running Lights (DRL) System Check

--

5

  1. Exchange the park lamp relay with a known good relay from the underhood junction block.
  2. Command the automatic lamp control to ON.

Do the park lamps light?

--

Go to Step 6

Go to Step 7

6

Replace the faulty relay?

--

Go to Daytime Running Lights (DRL) System Check

--

7

Replace the underhood junction block. Refer to Underhood Fuse Block Replacement in Engine Electrical.

Is the repair complete?

--

Go to Daytime Running Lights (DRL) System Check

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