Daytime Running Lamps (DRL) Inoperative (X88 and Z75)

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Step	Action	Yes	No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or 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	Carefully supply sufficient light to the ambient light sensor. Place the headlamps in the AUTO position. Start the engine. Does the system operate normally?	Go to Testing for Electrical Intermittents	Go to Step 3
3	Is only one daytime running lamp (DRL) inoperative?	Go to Step 4	Go to Step 5
4	Test the supply and ground circuits of the affected lamp for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 17	Go to Step 16
5	Ensure the park brake is not set. Install a scan tool. Turn ON the ignition, with the engine OFF. With the scan tool, observe the Park Brake Switch parameter in the Body Control Module (BCM) data list. Does the scan tool display RELEASED?	Go to Step 7	Go to Step 6
6	Test the signal circuit of the park brake switch for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 17	Go to Step 11
7	Turn OFF the ignition. Connect a 10-amp fused jumper wire between battery positive voltage and the DRL supply voltage circuit terminal of the DRL fuse. Do the DRL illuminate?	Go to Step 8	Go to Step 12
8	Restart the engine. Test the DRL relay control circuit of the DRL relay for a ground signal. Refer to Circuit Testing . Is a ground signal present?	Go to Step 15	Go to Step 9
9	Test the DRL relay control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 17	Go to Step 10
10	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 17	Go to Step 13
11	Inspect for poor connections at the harness connector of the park brake switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 17	Go to Step 14
12	Repair the DRL supply voltage circuit. Refer to Wiring Repairs . Did you complete the repair?	Go to Step 17	-
13	Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 17	-
14	Replace the park brake switch. Refer to Park Brake Warning Lamp Switch Replacement . Did you complete the replacement?	Go to Step 17	-
15	Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement . Did you complete the replacement?	Go to Step 17	-
16	Replace the inoperative DRL. Did you complete the replacement?	Go to Step 17	-
17	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3