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?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Remove the high/low beam headlamp relay from the underhood relay center.

Do the high beams turn off?

--

Go to Step 3

Go to Step 7

3

  1. Reinstall the high/low beam headlamp relay
  2. Disconnect the body control module (PZM) connector C2.

Do the high beams turn off?

--

Go to Step 4

Go to Step 5

4

Replace the body control module (PZM). Refer to Body Control Module Replacement in Body Control Systems.

Is the body control module replacement complete?

--

Go to Step 11

--

5

Inspect CKT 1969 (BLK/WHT) for a short to ground. Refer to Testing for Short to Ground Wiring Systems.

Is CKT 1969 OK?

--

Go to Step 6

Go to Step 10

6

Replace the high/low beam headlamp relay.

Is the repair complete?

--

Go to Step 11

--

7

Remove the DRL relay from the underhood relay center.

Do the high beams turn off?

--

Go to Step 8

Go to Step 9

8

Replace the DRL relay.

Is the repair complete?

--

Go to Step 11

--

9

Repair the short to voltage in CKT 11 (LT GRN). Refer to Wiring Repairs Wiring Systems.

Is the repair complete?

--

Go to Step 11

--

10

Repair the suspect wiring. Refer to Wiring Repairs Wiring Systems.

Is the repair complete?

--

Go to Step 11

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11

Operate the system in order to verify the repair. Did you correct the condition?

--

System OK.

Go to Step 2