Yukon headlights

the headlights in my wifes '98 yukon do not work in the on position… i’ve replaced the switch and the fuse is good… the drl still works and we limp along in the parking lamp position, but we have no high beam in this mode…

Could be corrosion in the lamp plugs. That’s not uncommon.

But I’m curious, have you tried changing the bulbs? I know it sounds dumb, but sometimes one bulb will go out and the driver not notice until the other goes out too, and then the driver thinks the headlights don’t work.

Have you checked to see if the headlight relay is working? The switch sends power to the relay which closes its contacts and completes the headlight circuit.

If all else checks out I might be tempted to look at the “auto” feature that many of these trucks had. It is that little bulb looking device in the center of the dash, cover this sensor with something (too simulate night) and see what happens.

this i have not tried because i do not know where to find the relay for the lights… any help is appreciated

The relay is a small box plugged into either your fuse block or under the hood inside a secondary fuse/relay box. The box cover will have the relay labeled.

Try to find a repair manual for your vehicle at your local auto parts store or sign up on alldata.com so you can see the electrical schematic. Makes this sort of problem much easier to figure out.

One other thought, try turning on the headlights with the engine not running and listen for the relay to click as you turn the headlight switch. That will help you find it. It might be clicking, but the relay contacts are burned. If you can find the relay along with a schematic, you can jump the relay contacts with a piece of wire and see if your headlights turn on.

Are all of your fuses good?

all of the fuses are good… i’ll try what you suggested after church… i’ll keep you posted thank you

i believe that i can hear the contacts working, but i’m not really sure if thats it. still no headlights…

Were you able to find the relay/fuse box that had the relays labeled? It will have other relays in it as well. Most likely under the hood.

The relays are little boxes that are about 1 inch by 1 1/2 inches.

Were you able to locate a manual for your Yukon? This will really help you. If not, keep alldata in mind.

Do you know how to use a voltmeter? If you can follow a schematic and use a voltmeter, you can figure this one out. Finding the relay is your first task.

Post back with your findings.

found the relay box, but none are labeled and regretfully the truck was bought used with no owners manual. i’ll get a haynes or chilton in the near future to get to the bottom of this problem… thank you for your help, it is really cool to have help when needed.

Did you look at the underside of the relay box cover. There should be a sticker with the relay configuration. Or perhaps they are outlined on the cover itself. If the cover is really dirty, clean it up a bit, see if anything is drawn up there.

I strongly suggest you search Ebay for a used Owners’ Manual. They can be had for VERY little money. I just purchased one for a 1999 Honda Civic for $7.40, shipping included.
See if the local library has a Haynes Repair Manual for your car. In my city, they carry Haynes Manuals for a whole lot of brands/models.

Good luck.