1991 Buick Roadmaster Headlight Cut-Off Relay Replacement Guide
Having headlight trouble with your 1991 Roadmaster? The issue might be a simple, inexpensive relay.
- A bad headlight relay can cause headlights to not turn on, flicker, or stay on permanently.
- This is not a common documented problem for the 1991 Roadmaster; failure is likely due to age.
- Replacement is extremely easy and affordable, making it a good first step in troubleshooting.
- Standard Ignition is a reputable aftermarket brand for this part.
Is Your Headlight Relay Failing?
On the 1991 Buick Roadmaster, the headlight system is generally reliable. Unlike some other vehicles, there are no widespread recalls or technical service bulletins (TSBs) for the headlight relay. However, after three decades, any electrical part can fail. A faulty headlight relay can mimic other problems, so it's important to recognize the signs.
Symptoms of a Bad Headlight Relay
A failing headlight relay can cause several distinct problems. The most common sign is when your headlights don't turn on at all, even with good bulbs and fuses. You might also experience headlights that flicker or cut out intermittently while you're driving. In other cases, the opposite happens: the headlights refuse to turn off even after you've shut off the car, which can drain your battery. Sometimes, a bad relay can affect only the high beams or low beams, or cause the headlights to appear dimmer than usual. If you hear a rapid clicking sound from the fuse box area when you try to turn on the lights, that can also point to a relay that is trying but failing to make a connection.
Choosing the Right Aftermarket Relay
For a vehicle like the 1991 Roadmaster, finding a new original equipment (OEM) relay from GM is highly unlikely. The good news is that high-quality aftermarket parts are available and affordable.
Brand Spotlight: Standard Ignition (SMP)
Standard Motor Products is a long-established brand in the auto parts industry, known for making reliable electrical components. For many domestic vehicles, their quality is considered equivalent to the original parts. When shopping for a new headlight relay, a part from Standard Ignition is a dependable choice that meets or exceeds the original specifications. Given the low cost of the part, it's a smart and affordable step in troubleshooting your headlight issues.
Estimated Replacement Costs
| New Aftermarket Relay | $19.82 - $23.29 |
| Shop Labor | $25 - $50 |
| Estimated Total | $45 - $75 |
Frequently Asked Questions
Where is the headlight cut-off relay located on my 1991 Roadmaster?
The headlight relay is typically a small, cube-shaped part plugged into a fuse box. On a 1991 Roadmaster, check the main fuse/relay center under the hood first. It may also be located in a secondary fuse panel under the dashboard on the driver's side. The relay's location should be marked on the fuse box cover diagram.
Is a bad headlight relay a common problem on the 1991 Roadmaster?
No, this does not appear to be a common failure point. Searches of NHTSA data and owner forums did not show a pattern of complaints about this specific part. Failures are more likely due to the age of the vehicle rather than a known design flaw.
Can I replace the headlight relay myself?
Yes, this is a very easy DIY job. Once you locate the relay, you simply pull the old one straight out and plug the new one in. No special tools are required. The most difficult part is often just identifying the correct relay to pull.
My high beams don't work. Is it the relay?
It could be, but you should also check the multifunction switch (the turn signal stalk) and the high-beam switch itself. A failure in the relay can sometimes affect only the high or low beams. However, problems with the switch in the steering column are also a possibility for high-beam-only issues.
Technical Specifications
Standard 4- or 5-pin blade-style multi-function relay.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Buick Roadmaster: