GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the Headlight Diagnostic System Check performed?

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Go to Step 2

Go to Headlight System Check

2

  1. Turn the headlamp switch to the HEAD position.
  2. Turn the headlamp dimmer switch to the HI position.
  3. Use a test lamp in order to backprobe between C201 and terminal E11 and ground.

Did the test lamp light?

--

Go to Step 3

Go to Step 4

3

Use a test lamp to backprobe between the underhood accessory junction block connector C2 terminal F4 and ground.

Did the test lamp light?

--

Go to Step 6

Go to Step  5

4

Inspect for a faulty connection or an open in CKT 11 between the headlamp dimmer switch and C201 terminal E13.

Is there a faulty connection or an open in CKT 11?

--

Go to Step 9

Go to Step 10

5

Repair the faulty connection or open in CKT 11 between C201 terminal E11 and the underhood accessory junction block harness connector C2 terminal F4.

Is the repair complete?

--

Go to Headlight System Check

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6

Use a test lamp to backprobe between the underhood accessory junction block connector C3 terminal B4 and ground and between terminal A4 and ground.

Does the test lamp light at both terminals?

--

Go to Step 7

Go to Step 8

7

  1. Disconnect both of the headlamp connectors.
  2. Use a test lamp in order to frontprobe terminal C of each connector to ground.

Does the test lamp light at both connectors?

--

Go to Headlamp Replacement

Go to Step 11

8

Replace the underhood accessory junction block.

Refer to Relay/Fuse Center Replacement in Wiring Systems.

Has the repair been made?

--

Go to Headlight System Check

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9

Repair a faulty connection or an open in CKT 11.

Has the repair been made?

--

Go to Headlight System Check

--

10

Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column-Tilt.

Has the repair been made?

--

Go to Headlight System Check

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11

  1. Repair an open in the circuit that would not light the test lamp.
  2. If the test lamp would light on one of the circuits, replace the headlamp on that circuit. Refer to Headlamp Replacement .

Has the repair been made?

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System OK

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