GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Vivant 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Low and High Beams Headlamps Inoperative

Step

Action

Values

Yes

No

1

Inspect fuses EF12, EF20, EF21, EF18, EF19.

Is any fuse blown?

--

Go to Step 2

Go to Step 3

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

Is the repair complete?

--

System OK

--

3
  1. Turn ON the low beam headlamps.
  2. Inspect the voltage at fuses EF18 and EF19.
  3. Inspect the voltage at fuses EF20 and EF21 with high beams selected.

Is the voltage at the headlamps within the value specified?

11-14 V

Go to Step 4

Go to Step 9

4
  1. Turn ON the low-beam headlamps.
  2. Inspect the voltage at the headlamp connector terminal 5
  3. Turn the high-beam headlamp ON.
  4. Inspect the voltage at headlamp connector terminal 4.

Is the battery voltage available at the headlamps within the value specified?

11-14 V

Go to Step 6

Go to Step 5

5

Repair the open circuit between fuses EF20, EF21, EF18, and EF19 and the headlamps.

Is the repair complete?

--

System OK

--

6

Use an ohmmeter to measure between ground and the headlamp connector terminal 6.

Is the resistance equal to the specified value?

0 ohms

Go to Step 8

Go to Step 7

7

Repair the ground circuit.

Is the repair complete?

--

System OK

--

8
  1. Replace the faulty headlamps. Refer to Headlamp Replacement .
  2. Inspect the charging system to make sure that charging voltage is not excessively high. Repair if necessary.

Is the repair complete?

--

System OK

--

9

Use a voltmeter to measure for power to the fuses EF12.

Is the voltage at fuse EF12 within the value specified?

11-14 V

Go to Step 11

Go to Step 10

10

Repair the power supply circuit to the fuse EF12.

Is the repair complete?

--

System OK

--

11

Temporarily substitute the illumination relay in place of the headlamp relay.

Do the headlamps operate with the substituted relay?

--

Go to Step 12

Go to Step 13

12

Install the illuminate relay in its original position, and install a new headlamp relay.

Is the repair complete?

--

System OK

--

13
  1. Return the illumination relay to its original position, but do not install the headlamp relay.
  2. Use a voltmeter to measure the headlamp relay connector for terminal 30.

Is the voltmeter within the value specified?

11-14 V

Go to Step 15

Go to Step 14

14

Replace the engine fuse block.

Is the repair complete?

--

System OK

--

15

With the headlamp relay removed, use a voltmeter to measure the headlamp relay connector for terminal 86.

Is the voltmeter within the value specified?

11-14 V

Go to Step 16

Go to Step 14

16
  1. With the headlamp relay removed, turn the headlamp switch to the low-beam position.
  2. Use an ohmmeter to measure the continuity between the connector for relay terminal 85 and ground.

Is the ohmmeter equal to the specified value?

0 ohms

Go to Step 22

Go to Step 17

17
  1. Reinstall the headlamp relay.
  2. Inspect the voltage at the headlamp switch connector C2 terminal 1.

Is the voltage within the specified value?

11-14 V

Go to Step 19

Go to Step 18

18

Repair the open circuit between headlamp relay terminal 85 and the headlamp switch connector C2 terminal 1.

Is the repair complete?

--

System OK

--

19
  1. Disconnect the headlamp switch connector C2.
  2. Turn the headlamps to the low-beam position.
  3. Use an ohmmeter to measure the continuity between terminals 1 and 2 of headlamp combination switch C2.

Does the ohmmeter equal to the specified value?

0 ohms

Go to Step 21

Go to Step 20

20

Replace the headlamp switch.

Is the repair complete?

--

System OK

--

21

Repair the open circuit between terminal 2 of headlamp switch connector C2 and ground.

Is the repair complete?

--

System OK

--

22

Inspect the voltage at headlamp switch connector C1, terminal 6.

Is the voltage within the specified value?

11-14 V

Go to Step 24

Go to Step 23

23

Repair the open circuit between, headlamp switch connector C1 and terminal 87 of the headlamp relay.

Is the repair complete?

--

System OK

--

24
  1. Disconnect headlamp switch connector C1.
  2. Turn the headlamps to the low-beam position.
  3. Connect an ohmmeter between terminals 5 and 6 of headlamp switch connector C1. Observe the reading on the ohmmeter.
  4. Turn the headlamps to the high-beam position.
  5. Connect an ohmmeter between terminals 4 and 6 of the headlamp switch. Observe the reading on the ohmmeter.

Is the ohmmeter show the specified value for both of the tests?

0 ohms

Go to Step 25

Go to Step 20

25

Repair the open circuit between the headlamp switch and fuses EF30, EF21, EF18, and EF19.

Is the repair complete?

--

System OK

--