How to find the relay for the headlights - Cars & Trucks

Brett has the answer to this. Bad headlight relay.

Brett Duxbury Mar 16, 2022
Hi Anonymous, check the headlight relay under the bonnet in the relay compartment . Get a voltmeter or 12v probe tester and see if coil on relay gets 12v from the head light switch
If no voltage at relay coil then check switch and the fuse.

https://www.google.com/search?q=1988+ford+festiva+headlight+relay+location

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there could be a black plastic box that has fuses but also you will find relays. From the relay you can find the socket that feeds 12v directly into the headlight and see if headlight is ok and if the relay is suppling 12v to the headlight. Also from the relay you can also check if the switch is supplying 12v to the relay coil with a voltmeter or a 12 volt probe tester. you may have a faulty relay but you could test this via a volt meter.
you may have blown globes by getting a wire and putting terminal connectors that match the relay legs and manually supplying the 12volts to the headlights from the relay socket you can test if the globes light up . So basically you are doing the relays job

images for Where is the headlight relay location

Headlight Relay Installiation Assist pt.1 - YouTube

? 9:04
www.youtube.com/watch?v=CuhmK2i4efA
Jan 19, 2010 - Uploaded by PBRepair.ca This is a video to assist in the installiation of a headlight relay. Being installed on a 1997 GSX-R 750, but the ...

Either the headlight relay is stuck on, or the security system's headlight control is shorted and keeping the headlight relay on. Find the headlight relay (probably in a fuse and relay box under the hood), remove it and check the contacts with an ohmmeter. They should read open in a good relay, but will read little or no resistance if the contacts have welded together ( a possible result of rapid on-off cycling).

Did you check the fuse box inside the cabin ? The book says the relay is in the fuse block but does not give a description.
Keep in mind the headlight relay only affects the headlights. The other lights you mentioned are on different fuses and not the headlight fuses.

It has a headlight switch. Pull the knob out and it goes from off, to parking, to headlights. A (foot) press switch on the floor controls the low and high beam. The (low) wattage of the headlights back then and not needing to run small wiring through the turn signal switch, allowed them not to require a relay to run the headlights. You have two relays. Your flasher (turn signal) relay - under the dash. And your horn relay mounted on the firewall.

There is a fuse for both the low and high beam headlights.
There is a relay for both as well.

The headlight switch feeds the relay.

Thank you the excellent symptom of the problem.

Yes,12 V. goes to the headlight switch.

the headlight pop-up circuit is different from the lights themselves. Check the headlight fuses in the engine compartment fuse box. If the fuses are good then check the headlight relay. It is in the same fuse box just behind the headlight fuses. (The headlight relay is the second relay from the right side of the fuse box. the relay at the far right is the electronic fuel injection main relay.)

where is the location of the headlamp relay on a 2001 Buick century

either the headlight relay is stuck on. or the daytime running light module or relay is bad. to confirm find the relay center and switch the headlight relay out with another relay with the same part# on it. there should several in the relay center with the same part #. If this fixes the problem get a replacement relay. if not try switching out the relay for the daytime running lights. if no dice then unplug the daytime running light module.

mike