Headlamps Inoperative - Low Beams

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	Verify that the low beam headlamps are inoperative. Do the low beam headlamps operate normally?	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 3
3	Is only one low beam headlamp inoperative?	Go to Step 4	Go to Step 5
4	Inspect the inoperative bulb for an open filament and connector for poor terminal contact and replace/repair as necessary. Refer to Headlamp Bulb Replacement (Envoy, Rainier) , Headlamp Bulb Replacement (TrailBlazer) or Wiring Repairs . If no problem is found, repair the open, high resistance or short to ground in the low beam headlamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 14	-
5	Test the headlamp 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?	Go to Step 14	Go to Step 6
6	Place the headlamp switch in the HEAD position. Connect a fused jumper from ground to the headlamp switch signal terminal of the headlamp switch connector. Do the low beam headlamps illuminate?	Go to Step 9	Go to Step 7
7	Connect a fused jumper from ground to the headlamp driver module control circuit terminal at the headlamp driver module (HDM) in the underhood fuse block. Do the low beam headlamps illuminate?	Go to Step 10	Go to Step 8
8	Test the headlamp driver module ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition?	Go to Step 14	Go to Step 12
9	Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 14	Go to Step 13
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?	Go to Step 14	Go to Step 11
11	Replace the BCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement?	Go to Step 14	-
12	Replace the HDM. Refer to Relay Replacement (Attached to Wire Harness) or Relay Replacement (Within an Electrical Center) . Did you complete the repair?	Go to Step 14	-
13	Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair?	Go to Step 14	-
14	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3