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

Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

1. Carefully supply sufficient light to the ambient light sensor.
2. Place the headlamps in the AUTO position.
3. Start the engine.

Does the system operate normally?

Go to Testing for Electrical Intermittents

Go to Step 3

Remove the DRL fuse in the underhood fuse block.

Do the DRL turn OFF?

Go to Step 4

Go to Step 7

1. Reinstall the DRL fuse.
2. Use the scan tool to observe the DRL Relay Command parameter while switching the headlamp switch back and forth several times between AUTO and HEAD.

Does the DRL parameter change states as expected?

Go to Step 5

Go to Step 6

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

Did you find and correct the condition?

Go to Step 10

Go to Step 8

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 10

Go to Step 9

Repair the DRL supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 10

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

Did you complete the replacement?

Go to Step 10

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

Did you complete the replacement?

Go to Step 10

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3