Caution: The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:

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

Connector End View Reference: Lighting Systems Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

1. Place the headlamp switch in the ON position.
2. Place the turn signal multi function dimmer switch in the low beam position.

Do the low beam headlamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

Is only one low beam headlamp inoperative?

Go to Step 4

Go to Step 8

1. Disconnect the forward lamps harness connector from the inoperative headlamp ballast.
2. Ensure that the headlamp switch is in the head lamp position.
3. Ensure that the headlamp turn signal multi function dimmer switch is in the LOW BEAM position.
4. Test the battery positive voltage circuit of the inoperative headlamp before the ballast connector for high resistance, an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 5

Test the headlamp low beam supply voltage circuit of the inoperative headlamp before the ballast connector for high resistance, an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 6

Test the ground circuit of the inoperative headlamp before the ballast connector for high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 7

Install a known good headlamp bulb. Refer to Headlamp Bulb Replacement .

Does the lamp operate properly?

Go to Step 19

Go to Step 12

1. Place the headlamp switch in the head lamp position.
2. Place the turn signal multi function headlamp dimmer switch in the low beam position.
3. With a scan tool, monitor the Low Beam Relay Command data parameter in the body control module (BCM) data list.

Does the scan tool display On?

Go to Step 17

Go to Step 9

1. Disconnect the multifunction switch.
2. Place the headlamp switch in the head lamp position.

Do the low beam headlamps illuminate?

Go to Step 13

Go to Step 10

Test the turn signal multi function headlamp dimmer switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 11

Test the turn signal multi function headlamp switch flash to pass signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 14

Inspect for poor connections at the harness connector of the ballast. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 15

Inspect for poor connections at the harness connector of the turn signal multi function headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 18

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Replace the headlamp ballast. Refer to Headlamp Replacement or Headlamp Bulb Replacement .

Did you complete the replacement?

Go to Step 19

--

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

Did you complete the replacement?

Go to Step 19

--

Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement .

Did you complete the replacement?

Go to Step 19

--

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

Did you complete the repair?

Go to Step 19

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3