Headlamps Inoperative - Low Beams

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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 Body Control System Connector End Views in Body Control System
1	Did you perform the Lighting Systems Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - Lighting Systems
2	Place the headlamp switch in the ON position. Place the dimmer switch in the low beam position. Do the low beam headlamps operate normally?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Is only one low beam headlamp inoperative?	Go to Step 4	Go to Step 5
4	Test the headlamp low beam supply voltage and ground circuits for high resistance, an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 16	Go to Step 9
5	Disconnect the headlamp low relay. Connect a test lamp between the control circuit of the headlamp low relay and the battery positive voltage circuit of the headlamp low relay connector. Does the test lamp illuminate?	Go to Step 14	Go to Step 6
6	Connect the headlamp low relay. Disconnect the multifunction switch. Place the headlamp switch in the HEAD position. Do the low beam headlamps illuminate?	Go to Step 10	Go to Step 7
7	Test the headlamp dimmer switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition?	Go to Step 16	Go to Step 8
8	Test the headlamp switch flash to pass signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition?	Go to Step 16	Go to Step 11
9	Inspect for poor connections at the harness connector of the inoperative bulb. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 16	Go to Step 12
10	Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 16	Go to Step 15
11	Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 16	Go to Step 13
12	Replace the inoperative bulb. Refer to Headlamp Assembly or Headlamp Bulb Replacement (Old Style) . Did you complete the replacement?	Go to Step 16	-
13	IMPORTANT: Perform the setup procedure for the BCM. Replace the BCM. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?	Go to Step 16	-
14	Replace the low beam headlamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the replacement?	Go to Step 16	-
15	Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair?	Go to Step 16	-
16	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3