GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

Schematic Reference: Headlights Schematics

Connector End View Reference: Component Connector End Views

1

Inspect fuses Ef20, left side headlamps, and Ef27, right side head lamps.

Is fuse Ef20 or Ef27 open?

--

Go to Step 2

Go to Step 3

2

  1. Inspect for a short circuit and repair if necessary.
  2. Replace the fuse.

Did you complete the repair?

--

System OK

--

3

Measure the voltage at fuses Ef20 and Ef27.

Does the voltage available at fuses Ef20 and Ef27 measure within the specified range?

11-14 V

Go to Step 4

Go to Step 9

4

  1. Disconnect both headlamp connectors.
  2. Turn the headlamps ON.
  3. Select the low beams.

Does the voltage at each headlamp connector terminal 5 measure within the specified range?

11-14 V

Go to Step 6

Go to Step 5

5

Repair the open circuit between fuses Ef20 or Ef27 and the low beam headlamps.

Did you complete the repair?

--

System OK

--

6

  1. Disconnect the headlamp connectors.
  2. Connect an ohmmeter between ground and either headlamp connector terminal 6.

Is the resistance equal to the specified value?

0 Ω

Go to Step 8

Go to Step 7

7

Repair the ground circuit.

Did you complete the repair?

--

System OK

--

8

Replace the faulty headlamps.

Did you complete the replacement?

--

System OK

--

9

  1. Disconnect the headlamp switch connector.
  2. Select the low beams.
  3. Use an ohmmeter to verify the continuity between terminals 6 and 5 of the headlamp switch.

Does the ohmmeter indicate the specified value?

0 Ω

Go to Step 10

Go to Step 11

10

Replace the headlamp combination switch.

Did you complete the replacement?

--

System OK

--

11

Repair the open circuit between fuses Ef20 and Ef27 and the headlamp switch connector terminal 5.

Did you complete the repair?

--

System OK

--