Headlights not working

RONALD DRENNAN

MEMBER
1998 CADILLAC DEVILLE
V8
2WD
AUTOMATIC
64,000 MILES

All the lights on my car work, except my Headlights. I can only operate my car in the daytime. They were working fine last week. I just bought the car in September from a used car lot. I pulled all the mini fuses from the fuse block under the hood. They were fine, nothing broken or burned out. When I pull out the Headlight knob to the first position, the running lights come on. When I pull out the knob again, the headlights do not come on. Also, I have the Twilight Lever turned off.

3 Replies

SQM

MECHANIC
6,383 POSTS

Hello,

There is a relay for the headlights located in the under-hood fuse box.
Check that relay, maybe you can swap it with a similar one next to it and see if the light comes on.
The relay can also be tested.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I have attached the diagrams below.

Please let me know of any questions.
Thank you.

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Friday, October 15th, 2021 AT 8:56 AM

RONALD DRENNAN

MEMBER
5 POSTS

Which one is the Headlight Relay Switch? A video would be nice. Finding it, testing it, how to replace it?

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Friday, October 15th, 2021 AT 9:17 AM

SQM

MECHANIC
6,383 POSTS

I have circled the relay on the chart below. It shows the orientation of it.
Also attached a picture of what the relay looks like.

This is a guide that shows how to test any relay step by step:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://youtu.be/Hlna_kUt7As

The relay will simply pull out just like a fuse.

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