Headlight Problem

RICK615

MEMBER
1997 CHEVROLET SUBURBAN
5.7L
V8
2WD
AUTOMATIC
293,000 MILES

My daytime running lights work with the switch in the off position. With the switch in the first on position all of the other lights come on along with the headlights. When the switch is placed into the final position (headlights on) all of the other lights stay on but the headlights go off. The dimmer switch has no effect. I replaced the main on/off switch and have the same results. I could not find a relay marked "headlights" and the 50 amp fuse is good. Where should I look and what should I test next? Thank you for your help

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi and thanks for using 2carpros.com

My first suspect is the day time lamp relay. It is located under the left side of the dash. I attached a picture of a portion of the wiring schematic showing it. If there is a relay with the same part number, switch them to see if that changes anything. Also, here is a link that shows how to check a relay.

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

Check that and let me know what you find. Also, you mentioned that the 50 amp fuse is good. Make sure there is power to the fuse also.

I don't know if you need them, but here are a few links you may find helpful.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Take care,
Joe

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Monday, January 28th, 2019 AT 7:18 PM

RICK615

MEMBER
3 POSTS

Thank you very much for your reply. Sorry it took me so long to get back to you but I was waiting for the ice to melt.
To answer your question, yes there is 12 volts on the 50 amp fuse under the hood. I removed the DRL relay and tested it. It works on the bench as it should. I then tested the socket and there was 12 volts on one of the coil contacts. I then replaced the coil, removed the "buzzer" module so I could hear the relay and it was moving as it should when I switched to the headlights from the "parking" lights. (Were you supposed to turn those on when you went parking with the girls? Just wondering.)
The circuit is working as it should up to this point. Do you have any other recommendations?

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Tuesday, February 5th, 2019 AT 2:44 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Welcome back:

Heck no. When parking, all lights should be out. LOL

I have to ask a question. Which of the following does your vehicle have?

Headlights - W/ Quad Headlamps
Headlights - W/ Sealed Beam Headlamps

They are two totally different wiring schematics.

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Tuesday, February 5th, 2019 AT 7:00 PM

RICK615

MEMBER
3 POSTS

Oh I have the Quad Headlamps with the super easy to change 9005 and 9006 bulbs, once your take the front end off!

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Tuesday, February 5th, 2019 AT 9:02 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Welcome back:

You made me laugh. My favorite is a Saab 9-3 where the front bumper cover needs removed.

Okay, I see only a few possibilities. First, you checked the DRL relay. Take a look at picture 1. Make sure power is available at pins H4 and H6.

2. Take a look at picture 2. That shows the headlight switch. The yellow wire that I highlighted should have power with the switch is all the way out. If it does, then the switch is good. Check that.

3. Look at picture 3. Here is what I need you to check. Make sure there is power to the highlighted wire which goes to lamp feed with the lights on. If there is, then check the ground for the DRL relay module. See location in image. If there is power in to the light feed and the ground is good, I suspect the relay module has failed.

I have one more suggestion. I have seen so many "new" headlight switches which are either put together wrong internally or poorly designed. The result is basically what you have described. If you can, I would try another switch or remove the one you have and check it for continuity in the on position.

Let me know if this helps, if you have other questions, or need additional information.

Take care,
Joe

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