* Faulty Headlight Switch: This is a common cause. The switch might be failing to completely break the circuit, allowing power to continue flowing to the headlights even when it's in the "off" position. The switch itself could be worn or internally shorted.
* Wiring Problem: A short circuit or a damaged wire in the headlight circuit could be bypassing the switch. This could be anywhere between the switch and the headlights, including within the steering column or under the dashboard. A wire might be chafing against metal, creating a short.
* Relay Issue: The headlight circuit likely uses a relay. A stuck relay, meaning it remains closed even when it shouldn't, will continuously supply power to the headlights.
* Body Control Module (BCM) Malfunction: The BCM controls many electrical functions in modern cars. A malfunctioning BCM could be sending incorrect signals to the headlight circuit, keeping them on. This is less likely but possible.
* Aftermarket Modifications: If any aftermarket accessories or modifications were added to the car's electrical system, they could be interfering with the headlight circuit.
* Ignition Switch: While less likely than the other options, a faulty ignition switch could be failing to fully cut power to certain circuits, including the headlights.
Troubleshooting Steps:
1. Check the Headlight Switch: Try carefully wiggling the headlight switch while it's in the "off" position. If the lights flicker or go off temporarily, the switch is highly suspect.
2. Check Fuses: Inspect the fuses related to the headlights. A blown fuse might seem counterintuitive, but a short circuit could blow the fuse and then the short itself might still allow the lights to stay on (depending on the location of the short).
3. Visual Inspection of Wiring: If you're comfortable working with car wiring, carefully inspect the wiring harness leading to and from the headlight switch and the headlights themselves. Look for any frayed, melted, or otherwise damaged wires. Caution: Disconnect the negative battery terminal before doing this.
4. Relay Check: Locate the headlight relay (consult your owner's manual or a wiring diagram). You can try swapping it with a known good relay of the same type (if you have one).
What NOT to do:
* Don't keep driving with the headlights on. This will drain your battery, leaving you stranded.
Recommendation:
Unless you're comfortable working with car electrical systems, it's best to take your 1995 Buick Riviera to a qualified mechanic. They have the tools and expertise to diagnose and repair the problem safely and effectively. Describing the issue clearly – that the headlights remain on even with the ignition off – will help them pinpoint the cause.
