GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the Headlamp Diagnostic System Check performed?

--

Go to Step 2

Go to Headlight System Check

2

Inspect the HEADLAMP circuit breaker.

Is the circuit breaker open?

--

Go to Step 3

Go to Step 4

3

Repair a short to ground in CKT 2340.

Is the repair complete?

--

Go to Headlight System Check

--

4

  1. Turn the headlamp switch to the HEAD position.
  2. Use a test lamp in order to backprobe between C201 terminal E13 and ground.

Did the test lamp light?

--

Go to Step 8

Go to Step 5

5

Use a test lamp in order to backprobe between the headlamp dimmer switch harness connector terminal L and ground.

Did the test lamp light?

--

Go to Step 7

Go to Step 6

6

Use a test lamp in order to backprobe between the headlamp and instrument panel dimmer switch harness connector terminal N and ground.

Did the test lamp light?

--

Go to Step 9

Go to Step 10

7

Repair the faulty connection and/or open in CKT 10 between C201 terminal E13 and the headlamp dimmer switch connector terminal L.

Is the repair complete?

--

Go to Headlight System Check

--

8

  1. Use a test lamp in order to backprobe between C201 terminal E12 and ground.
  2. Activate the dimmer switch.

Did the test lamp light?

--

Go to Step  11

Go to Step 9

9

Replace the headlamp dimmer switch. Refer to Headlamp Switch Replacement .

Is the repair complete?

--

Go to Headlight System Check

--

10

Repair the faulty connection or open in CKT 2340.

Is the repair complete?

--

Go to Headlight System Check

--

11

  1. Use a test lamp in order to backprobe between C201 terminal E11 and ground.
  2. Activate the dimmer switch.

Did the test lamp light?

--

Go to Step 12

Go to Step 9

12

If the test lamp was lit in either Step 8 or Step 11, refer to Headlamps Inoperative - Low Beams or Headlamps Inoperative - High Beams .

Was the test lamp lit in Step 8 or Step 11?

--

Go to Headlamps Inoperative - Low Beams or Headlamps Inoperative - High Beams

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