GM Service Manual Online
For 1990-2009 cars only

Headlamps Inoperative - Low Beams Domestic

Step

Action

Value(s)

Yes

No

1

Was the headlamp system diagnostic check performed?

--

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 LOW position.
  3. Use a test lamp in order to backprobe between C201 terminal E12 and ground.

Did the test lamp light?

--

Go to Step 3

Go to Step 4

3

Use a test lamp in order to backprobe between the underhood accessory junction block connector C2 terminal F8 and ground.

Did the test lamp light?

--

Go to Step 6

Go to Step 5

4

Inspect for the following conditions in CKT 12 between the headlamp dimmer switch and C201 terminal E13:

    • A faulty connection
    • An open

Is there a faulty connection or an open in CKT 12?

--

Go to Step 9

Go to Step 10

5

Repair the following conditions in CKT 12 between C201 terminal E12 and the underhood accessory junction block harness connector C2 terminal F4:

    • A faulty connection
    • An open

Is the repair complete?

--

Go to Headlight System Check

--

6

Use a test lamp to backprobe between the underhood accessory junction block connector C3 terminal B8 and ground, and terminal A8 and ground.

Did 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 B of each connector to ground.

Did 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

Is the repair complete?

--

Go to Headlight System Check

--

9

Repair a faulty connection or open in CKT 12.

Is the repair complete?

--

Go to Headlight System Check

--

10

Replace the headlamp dimmer switch.

Is the repair complete?

--

Go to Headlight System Check

--

11

  1. Repair an open in the circuit that would not light the test lamp.
  2. If the test lamp would light on one circuit, replace the headlamp on that circuit.

Is the repair complete?

--

System OK

--

Headlamps Inoperative - Low Beams Export

Step

Action

Value(s)

Yes

No

1

Was the headlamp system diagnostic check performed?

--

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 LOW position.
  3. Use a test lamp in order to backprobe between C201 terminal E12 and ground.

Did the test lamp light?

--

Go to Step 3

Go to Step 4

3

Repair the following conditions in CKT 12 between C201 terminal E12 and the fuse block terminal C1:

    • An open
    • A poor connection

Has the repair been made and the system rechecked?

--

System OK

--

4

Inspect for the following conditions in CKT 12 between the headlamp dimmer switch and C201 terminal E12:

    • An open
    • A poor connection

Is there a poor connection or an open in CKT 12?

--

Go to Step 5

Go to Step 6

5

Repair the following conditions in CKT 12 between C201 terminal E12 and the headlamp dimmer switch:

    • A poor connection
    • An open

Has the repair been made and the system rechecked?

--

System OK

--

6

Replace the headlamp dimmer switch.

Has the repair been made and the system rechecked?

--

System OK

--