Headlamps Inoperative - Low Beams

WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. 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: Master Electrical Component List
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Turn ON the headlamps. Ensure that the headlamp dimmer switch is in the LOW position. Do both low beam headlamps illuminate?	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 3
3	Is only one low beam headlamp inoperative?	Go to Step 13	Go to Step 4
4	Disconnect the lamps switch assembly. Install a jumper between the headlamp switch headlamps ON signal circuit and ground. Do the low beam headlamps illuminate?	Go to Step 9	Go to Step 5
5	Test for a poor connection, an open or a short to battery positive voltage in the headlamp switch headlamps ON signal circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 19	Go to Step 6
6	Reconnect the lamp switch assembly. Disconnect the body control module (BCM) connector C1. Install a jumper between the headlamp module control circuit and ground. Do the low beam headlamps illuminate?	Go to Step 18	Go to Step 7
7	Remove the headlamp module. Install a fused jumper between battery positive voltage and the switched low beam voltage supply circuit. Do the low beam headlamps illuminate?	Go to Step 8	Go to Step 11
8	Test for the following in the headlamp module control circuit: An open A poor connection A short to ground Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 19	Go to Step 10
9	Inspect for a poor connection at the harness connector of the lamp switch assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 19	Go to Step 14
10	Inspect for a poor connection at the headlamp module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 19	Go to Step 15
11	Test for a short to ground in the low beam voltage supply circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 19	Go to Step 12
12	Inspect for a poor connection 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 19	Go to Step 17
13	Inspect the inoperative low beam headlamp voltage supply and ground circuit for a high resistance, a short to ground or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 19	Go to Step 16
14	Replace the lamp switch assembly. Refer to Headlamp Switch Replacement . Did you complete the replacement?	Go to Step 19	-
15	Replace the headlamp module. 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 19	-
16	Replace the inoperative low beam headlamp. Refer to Headlamp Assembly or Headlamp Bulb Replacement . Did you complete the replacement?	Go to Step 19	-
17	Replace the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections . Did you complete the replacement?	Go to Step 19	-
18	Replace the BCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement?	Go to Step 19	-
19	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3