GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 GTO 🢒 Body 🢒 Lighting Systems 🢒 Automatic Lamp Control Inoperative

Step

Action

Values

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you perform the Lighting System Diagnostic Starting Point?

--

Go to Step 2

Go to Diagnostic Starting Point - Lighting Systems

2

Verify the fault is present.

Does the system operate normally?

--

Go to Testing for Electrical Intermittents in Wiring Systems

Go to Step 3

3

Do the headlamps function correctly when the headlamp switch is in the ON or OFF position?

--

Go to Step 4

Low Beams Inoperative

4
  1. Turn the ignition to the ON position.
  2. Turn the headlamp switch to the AUTO position.
  3. Cover the ambient light sensor.

Do the headlamps turn ON?

--

Go to Step 5

Go to Step 8

5
  1. With the ignition on and the headlamp switch in the AUTO position, uncover the light sensor.
  2. Shine a light on the light sensor.

Do the headlamps turn OFF?

--

Go to Step 6

Go to Step 18

6
  1. Connect the Tech 2 to the data link connector (DLC).
  2. Using the Tech 2, with the Tech 2 connected, set the headlamp delay time to 5 seconds.
  3. With the headlamp switch in the AUTO position, cover the light sensor to turn on the headlamps.
  4. Turn the ignition OFF.
  5. Open then close the driver door.

Do the headlamps turn OFF after 5 seconds?

--

Go to Step 7

Go to Step 15

7
  1. With the Tech 2 still connected, set the headlamp delay time to 10 seconds.
  2. Turn the headlamp switch to the ON position.
  3. Turn the ignition OFF.
  4. Close both doors.
  5. Open then close the driver door.
  6. Wait for the headlamps to turn OFF.
  7. Lock the doors using the lock button on the transmitter.
  8. Unlock the doors using the unlock button on the transmitter.

Do the headlamps turn ON for 10 seconds?

Go to Step 27

Go to Step 26

8

Using a Tech 2, command the automatic headlamps ON.

Did the headlamps turn ON?

--

Go to Step 12

Go to Step 9

9

With the headlamp switch in the AUTO position, the light sensor covered and Tech 2 connected, exit to the body control module (BCM) menu and select Data Display/Headlamps/Auto Headlamp data display.

Does the Tech 2 display ON?

--

Go to Step 10

Go to Step 12

10

With the headlamp switch in the AUTO position, back-probe the BCM connector terminal C1-6, with a fused jumper wire to ground.

Do the headlamps turn ON?

--

Go to Step 26

Go to Step 11

11
  1. Disconnect the headlamp switch.
  2. With the headlamp switch in the AUTO position, back-probe between headlamp switch terminals C1-4 and C1-2 with an ohmmeter.

Are the values as specified?

Less than 1 ohms

Go to Step 23

Go to Step 24

12
  1. With the Tech 2 connected, exit to the BCM menu and select Data Display/Headlamps/Ambient Light Sensor.
  2. Cover the light sensor.
  3. Uncover and shine a light on the light sensor.

Are the values as specified?

Covered = 0 V

Uncovered = between 0-5 V

Go to Step 26

Go to Step 13

13
  1. Disconnect the light sensor connector.
  2. Back-probe the light sensor terminal C1-6 with a fused jumper wire to battery voltage.
  3. Back-probe the light sensor terminal C1-4, circuit 1784 with a voltmeter to ground.
  4. Turn the ignition ON.
  5. Cover the light sensor.
  6. Uncover and shine a light on the light sensor.

Are the values as specified?

Covered = less than 0.5 V Uncovered = above 0.5 V, up to 5 V

Go to Step 14

Go to Step 25

14

Inspect circuit 1784 for open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and complete the repair?

--

Go to Step 27

Go to Step 26

15

In Step 3, did the headlamps turn OFF after longer than 5 seconds?

--

Go to Step 16

Go to Step 26

16
  1. Disconnect the headlamp switch connector.
  2. Back-probe headlamp switch connector terminal C1-5, circuit 306 with an ohmmeter to ground.

Is the value as specified?

Less than 1 ohms

Go to Step 17

Go to Step 24

17

Inspect circuit 306 for open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and complete the repair?

--

Go to Step 27

Go to Step 26

18

Using the Tech 2 command the automatic headlamps OFF.

Do the headlamps turn OFF?

--

Go to Step 19

Go to Step 20

19
  1. Back-probe the BCM connector terminal C2-2, circuit 1784 with a voltmeter to ground.
  2. Turn the ignition ON.
  3. Shine a light on the light sensor.

Is the value as specified?

More than 0.5 V, up to 5 V

Go to Step 26

Go to Step 13

20

With the Tech 2 connected, exit to the BCM menu and select Data Display/Headlamps/Headlamp

Does Tech 2 display OFF?

--

Go to Step 21

Go to Step 26

21
  1. Disconnect the headlamp switch connector.
  2. Back-probe headlamp switch connector terminal C1-2, circuit 103 with an ohmmeter to ground.

Is the value as specified?

Less than 1 ohms

Go to Step 22

Go to Step 24

22

Inspect circuit 103 for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and complete the repair?

--

Go to Step 27

Go to Step 26

23

Repair the open or high resistance in circuit 103. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and complete the repair?

--

Go to Step 27

--

24

Replace the headlamp switch. Refer to Headlamp Switch Replacement

Did you complete the repair?

--

Go to Step 27

--

25

Replace the ambient light sensor.

Did you complete the replacement?

--

Go to Step 27

--

26

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 27

--

27

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3