GM Service Manual Online
For 1990-2009 cars only

Headlamps Inoperative - Low Beams Standard Headlamps

Step

Action

Yes

No

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

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Are both low beam headlamps inoperative?

Go to Step 3

Go to Step 8

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Turn ON the headlamps.
  4. With the scan tool, observe the Headlamp Switch parameter in the instrument panel module (IPM) Inputs data list.

Does the data parameter display ON?

Go to Step 5

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the turn signal/multifunction switch C3 harness connector.
  3. Connect a 3-amp fused jumper between the headlamp ON signal circuit and the ground circuit of the turn signal/multifunction switch at the C3 harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. With the scan tool, observe the Headlamp Switch parameter in the IPM inputs data list.

Does the Headlamp Switch parameter display ON?

Go to Step 14

Go to Step 11

5

  1. Turn OFF the ignition.
  2. Disconnect the headlamp LOW BEAM relay located in the underhood fuse block. Refer to Relay Replacement in Wiring Systems.
  3. Connect a test lamp between the headlamp low beam relay control side supply voltage circuit and the headlamp low beam relay control circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. Turn ON the low beam headlamps.

Does the test lamp illuminate?

Go to Step 6

Go to Step 10

6

Connect a test lamp between the headlamp low beam relay switch side supply voltage circuit and ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 19

7

  1. Turn OFF the ignition.
  2. Connect a 40-amp fused jumper between the headlamp low beam relay switch side supply voltage circuit and the headlamp low beam supply voltage circuit.
  3. Turn ON the ignition, with the engine OFF.

Do both of the low beam headlamps illuminate?

Go to Step 15

Go to Step 8

8

  1. Disconnect the inoperative low beam headlamp bulb.
  2. Connect a test lamp between the low beam headlamp supply voltage circuit at the inoperative low beam headlamp bulb and the ground circuit of the inoperative low beam headlamp bulb.

Does the test lamp illuminate?

Go to Step 17

Go to Step 9

9

Test the headlamp low beam supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 18

10

Test the headlamp low beam relay control circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 13

11

Test the turn signal/multifunction switch ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 12

12

Test the turn signal/multifunction switch headlamp ON signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 13

13

Test the twilight sentinel delay signal circuit of the IPM for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 16

14

Inspect for poor connections at the C 3 harness connector of the turn signal/multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 20

15

Inspect for poor connections at the headlamp low beam relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 21

16

Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 22

17

Inspect for poor connections at the harness connector of the inoperative low beam headlamp bulb. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 23

18

Locate and repair an open or high resistance in the headlamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 24

--

19

Locate and repair an open or high resistance in the switch side supply voltage circuit of the headlamp low beam relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 24

--

20

Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 24

--

21

Replace the headlamp low beam relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 24

--

22

Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 24

--

23

Replace the inoperative low beam headlamp bulb. Refer to Headlamp Bulb Replacement .

Did you complete the replacement?

Go to Step 24

--

24

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Headlamps Inoperative - Low Beams HID Headlamps

Step

Action

Yes

No

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

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Are both low beam headlamps inoperative?

Go to Step 3

Go to Step 8

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Turn ON the headlamps.
  4. With the scan tool, observe the Headlamp Switch parameter in the instrument panel module (IPM) Inputs data list.

Does the data parameter display ON?

Go to Step 5

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the turn signal/multifunction switch C3 harness connector.
  3. Connect a 3-amp fused jumper between the headlamp ON signal circuit and the ground circuit of the turn signal/multifunction switch at the C3 harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. With the scan tool, observe the Headlamp Switch parameter in the IPM inputs data list.

Does the Headlamp Switch parameter display ON?

Go to Step 14

Go to Step 11

5

  1. Turn OFF the ignition.
  2. Disconnect the headlamp LOW BEAM relay located in the underhood fuse block. Refer to Relay Replacement in Wiring Systems.
  3. Connect a test lamp between the headlamp low beam relay control side supply voltage circuit and the headlamp low beam relay control circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. Turn ON the low beam headlamps.

Does the test lamp illuminate?

Go to Step 6

Go to Step 10

6

Connect a test lamp between the headlamp low beam relay switch side supply voltage circuit and ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 19

7

  1. Turn OFF the ignition.
  2. Connect a 40-amp fused jumper between the headlamp low beam relay switch side supply voltage circuit and the headlamp low beam supply voltage circuit.
  3. Turn ON the ignition, with the engine OFF.

Do both of the low beam headlamps illuminate?

Go to Step 15

Go to Step 8

8

  1. Disconnect the inoperative low beam headlamp.
  2. Connect a test lamp between the low beam headlamp supply voltage circuit at the inoperative low beam headlamp and the ground circuit of the inoperative low beam headlamp.

Does the test lamp illuminate?

Go to Step 17

Go to Step 9

9

Test the headlamp low beam supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 18

10

Test the headlamp low beam relay control circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 13

11

Test the turn signal/multifunction switch ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 12

12

Test the turn signal/multifunction switch headlamp ON signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 13

13

Test the twilight sentinel delay signal circuit of the IPM for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 16

14

Inspect for poor connections at the C3 harness connector of the turn signal/multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 20

15

Inspect for poor connections at the headlamp low beam relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 21

16

Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 22

17

Inspect for poor connections at the harness connector of the inoperative low beam high intensity discharge (HID) headlamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 25

Go to Step 23

18

Locate and repair an open or high resistance in the headlamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 25

--

19

Locate and repair an open or high resistance in the switch side supply voltage circuit of the headlamp low beam relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 25

--

20

Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 25

--

21

Replace the headlamp low beam relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 25

--

22

Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 25

--

23

Replace the inoperative HID headlamp arc tube. Refer to High Intensity Discharge Headlamp Ballast Replacement .

Do the low beam headlamps operate properly?

Go to Step 25

Go to Step 24

24

Replace the inoperative HID headlamp ballast. Refer to High Intensity Discharge Headlamp Ballast Replacement .

Did you complete the replacement?

Go to Step 25

--

25

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2