For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Exterior Lights Schematics . Connector End View Reference: Component Connector End Views .
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle .
2 |

1. Place the headlamp switch in the ON position.
2. Activate the high beam headlamps.

Do the high beam headlamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections .

Go to Step 3

3 | Is only one high beam headlamp inoperative? | Go to Step 4 | Go to Step 5
4 | Test the high beam headlamp supply voltage circuit for high resistance, an open or a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | System OK | Go to Step 8
5 |

1. Place the headlamp switch in the ON position.
2. Activate the high beam headlamps.
3. With a scan tool, monitor the High Beam Relay Command data parameter in the body control module (BCM) data list.

Does the scan tool display On?

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

Go to Step 6

6 | Test the headlamp dimmer switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | System OK | Go to Step 7
7 |

1. Place the headlamp switch in the ON position.
2. Connect a fused jumper from ground to the headlamp dimmer switch signal terminal of the headlamp dimmer switch connector.

Do the high beam headlamps illuminate?

Go to Step 9

Go to Step 10

8 | Inspect for poor connections at the harness connector of the inoperative bulb. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | System OK | Replace the high beam bulb. Refer to Headlamp Bulb Replacement .
9 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | System OK | Replace the headlamp dimmer switch. Refer to Turn Signal Switch Replacement .
10 | 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? | System OK | Replace the BCM. Refer to Control Module References , for replacement, setup, and programming.