GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Acadia - 2WD 🢒 Body Systems 🢒 Lighting 🢒 Automatic Lamp Control Inoperative

Step

Action

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference: Lighting Systems Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Cover the ambient light sensor.
  2. Place the headlamp switch in the OFF position.
  3. Turn ON the ignition, with the engine OFF.
  4. Wait 20 seconds.

Do the headlamps and park lamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Are both the headlamps and park lamps inoperative in the AUTO position?

Go to Step 4

Go to Step 5

4
  1. Connect a scan tool.
  2. Observe the ambient light sensor parameter in the Exterior Lighting data list.

Is the parameter 3.66 volts or greater?

Go to Step 20

Go to Step 19

5

Are only the headlamps inoperative in the AUTO position?

Go to Step 6

Go to Step 11

6

Do the headlamps operate properly when the headlamp switch is placed in the headlamp ON position?

Go to Step 7

Go to Headlamps Inoperative - Low Beams

7
  1. Disconnect the headlamp relay.
  2. Connect a 15-amp fused jumper wire between the headlamp switch signal circuit of the headlamp HID/LO BEAM relay and a good ground.

Do the headlamps illuminate?

Go to Step 8

Go to Step 16

8

Probe the headlamp relay control circuit of the HID/LO BEAM relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 17

9

Connect a test lamp between the HID/LO BEAM relay control circuit of the headlamp relay and the coil side ground circuit of the headlamp relay.

Does the test lamp illuminate?

Go to Step 10

Go to Step 24

10

Connect a test lamp between the HID/LO BEAM headlamp relay control circuit of the headlamp relay and the switch side ground circuit of the headlamp relay.

Does the test lamp illuminate?

Go to Step 21

Go to Step 24

11

Do the park lamps operate properly when the headlamp switch is placed in the PARK position?

Go to Step 12

Go to Park, License, and Tail Lamps Inoperative

12
  1. Disconnect the PRK LAMP relay.
  2. Probe the switch side battery positive voltage circuit of the PRK LAMP relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 19

13
  1. Disconnect the PRK LAMP relay.
  2. Probe the coil side battery positive voltage circuit of the PRK LAMP relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 14

Go to Step 19

14

Connect a test lamp between the switch side battery positive voltage circuit of the PRK LAMP relay and the control circuit of the PRK LAMP relay.

Does the test lamp illuminate?

Go to Step 15

Go to Step 19

15

Connect a 15-amp fused jumper wire between the switch side battery positive voltage circuit of the PRKLAMP relay and the park lamp supply voltage circuit of the PRK LAMP relay.

Do the park lamps illuminate?

Go to Step 22

Go to Step 18

16

Test for an open or high resistance in the headlamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 23

17

Test for the following in the HID/LO BEAM headlamp low beam relay control circuit:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 19

18

Test for the following in the park lamp supply voltage circuit:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 19

19

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 25

20

Inspect for poor connections at the harness connector of the ambient light sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 26

21

Inspect for poor connections at the HID/LO BEAM headlamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 27

22

Inspect for poor connections at the PRK LAMP relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 27

23

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 29

Go to Step 28

24

Repair an open or high resistance in the ground circuit of the headlamp relay. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 29

--

25

Replace the BCM. Refer to Control Module References for BCM replacement, setup, and programming.

Did you complete the replacement?

Go to Step 29

--

26

Replace the ambient light sensor. Refer to Daytime Running Lamp (DRL) Ambient Light Sensor Replacement .

Did you complete the replacement?

Go to Step 29

--

27

Replace the appropriate relay. Refer to Relay Replacement

Did you complete the replacement?

Go to Step 29

--

28

Replace the headlamp switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the replacement?

Go to Step 29

--

29

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2