1. The Obvious Checks:
* Fuses: This is the absolute first step. Check the fuse box (usually under the dash or in the engine compartment) for blown fuses related to the headlights. The fuse rating should be printed on the fuse itself and/or in the owner's manual or under the fuse box cover. Use a test light or multimeter to confirm if the fuse is blown before replacing it. Don't just rely on visual inspection – a blown fuse might not always be obvious.
* Lightswitch: Try all the light switch positions (parking lights, headlights, high beams). A faulty switch is a common cause. If the parking lights work but not the headlights, the problem likely isn't the fuse.
* Bulbs: Inspect both headlights. It's possible one or both bulbs have burned out. Replace them with known good bulbs of the correct type (refer to your owner's manual). Note that some cars have different bulbs for high and low beams within the same headlight assembly.
* Battery: Ensure the battery is adequately charged. A weak battery can cause dimming or failure of the lights, especially if the car's electrical system is already stressed.
2. Intermediate Checks:
* Wiring: Visually inspect the wiring harness leading to the headlights for any obvious damage (breaks, fraying, corrosion). Pay close attention to the connections at the headlight assemblies and the bulkhead connector (where the wiring enters the car's body). Corrosion is a common enemy of older vehicles. Clean any corroded connections with a wire brush and dielectric grease.
* Grounds: Poor ground connections are a frequent culprit. Headlight grounds are usually located on the car's chassis near the headlight assemblies. Clean these ground points thoroughly. You might need a jumper wire temporarily to test if a poor ground is the issue.
* Multi-meter: Use a multimeter to check for voltage at the headlight connectors. With the headlights switched on, you should have battery voltage (typically around 12V) at the connector. If you don't, the problem lies somewhere between the light switch and the headlight.
3. Advanced Checks (requiring more electrical knowledge and tools):
* Headlight Relay (if equipped): Some '81 Regals might have relays for the headlights. Locate and test the relay using a multimeter or by swapping it with a known good relay (if you have spares).
* Light Switch Testing: Testing the light switch requires removing it from the dash and using a multimeter to check its internal circuits. This is more involved and requires some electrical knowledge. A wiring diagram is essential.
* Wiring Harness Tracing: If all else fails, you might need to trace the wiring harness from the light switch to the headlights to pinpoint a break or short in the wiring. A wiring diagram is absolutely essential for this.
Resources:
* Owner's Manual: Your owner's manual should have a fuse box diagram and information about the headlight system.
* Repair Manual: A Haynes or Chilton repair manual for your specific year and model Buick Regal will provide detailed wiring diagrams and troubleshooting information.
* Online Forums: Search online forums dedicated to classic Buicks. Owners have likely encountered and solved similar problems.
Safety First:
* Disconnect the battery's negative terminal before working on any electrical components to prevent shorts and accidental shocks.
* Be careful when working near hot engine components.
* If you're not comfortable working with car electrical systems, take it to a qualified mechanic. Troubleshooting electrical problems can be tricky, and misdiagnosis can lead to further damage.
By following these steps systematically, you should be able to isolate the cause of your inoperative headlights and get them working again. Remember to consult your owner's manual and/or a repair manual for specific information regarding your Buick Regal's electrical system.
