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

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

Are any DTCs present?

--

Go to Step 2

Go to Step 3

2

Refer to Body Control Module System Check in Body Control System.

Is the repair complete?

--

Go to Exterior Lights System Check

--

3

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

Do the parking lamps light?

--

Go to Step 4

Go to Step 5

4

Replace the ambient light sensor.

Is the repair complete?

--

Go to Exterior Lights System Check

--

5

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

Do the parking lamps light?

--

Go to Step 6

Go to Step 7

6

Replace the faulty relay.

Is the repair complete?

--

Go to Exterior Lights System Check

--

7

Replace the underhood junction block. Refer to Relay/Fuse Center Replacement in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--