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 park, tail and side marker lamps are inoperative.

Do the park, tail and side marker lamps operate normally?

--

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

Go to Step 3

3

Is the PARK LP fuse in the underhood fuse block good?

--

Go to Step 5

Go to Step 4

4

Locate and repair short to ground in CKT 240 between the underhood fuse block and the headlamp switch or CKT 74 between the headlamp switch and the under hood fuse block. Refer to Circuit Testing in Wiring Systems.

Is the repair complete?

--

Go to Step 10

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5

  1. Disconnect the headlamp switch.
  2. Connect a J 39200 Digital Multimeter (DMM) from the headlamp switch connector terminal B to ground. Refer to Circuit Testing in Wiring Systems.

Does voltage measure the specified value?

B+

Go to Step 7

Go to Step 6

6

Locate and repair open or high resistance in CKT 240. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 10

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7

Connect a fused jumper between the headlamp switch connector terminal A and terminal B.

Do the lamps light?

--

Go to Step 9

Go to Step 8

8

Locate and repair open or high resistance in CKT 74. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 10

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9

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Is the repair complete?

--

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3