1. Turn the ignition OFF.
2. Connect a scan tool.
3. Turn the ignition to the ON position.
4. Using the scan tool, check for any DTCs in the body control module (BCM).

Does the scan tool show any DTCs ?

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Go to Diagnostic System Check - Body Control System in Body Control System

Go to Step 2

1. Ensure the headlamp switch is in the AUTO position
2. Using the scan tool command the head lamp power relay ON.

Does the headlamps come on?

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Go to Step 3

Go to Headlamps Inoperative in Low Light Conditions

Using the scan tool, read the flash to pass switch status as you move the switch.

Does the scan tool show the switch status change?

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Go to Step 9

Go to Step 4

Connect a test lamp (back probe) from terminal E10 of the headlamp dimmer switch connector C201C to ground.

Does the test lamp light?

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Go to Step 6

Go to Step 5

Locate and repair CKT 1140 (ORN) for an open between the underhood buseed electrical center (UBEC) and the switch.

Is the repair complete?

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System OK

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1. Connect a test lamp (back probe) from terminal A8 of the headlamp dimmer switch connector C201A to ground.
2. While probing, move the flash to pass switch.

Does the test lamp light?

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Go to Step 8

Go to Step 7

Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in steering wheel and column - tilt.

Is the repair complete?

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System OK

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Locate and repair the open in CKT 1356 (BRN) between the switch and the BCM.

If no open is found, replace the BCM. Refer to Body Control Module Replacement in Body Control Systems.

Is the repair complete?

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System OK

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

Is the repair complete?

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System OK

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