For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views and Data Communication Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

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

Do the low beam headlamp bulbs illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3 | With a scan tool, observe the DRL Status parameter in the body control module (BCM) data list. Does the scan tool display On? | Go to Step 4 | Go to Step 7
4 | Test the DRL supply voltage circuit for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 5
5 | 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 9 | Go to Step 6
6 | Replace the DRL relay. Refer to Relay Replacement . Did you complete the repair? | Go to Step 9 | --
7 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 8
8 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | --
9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3