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My brake lights turn on when I turn my head lights on

I have a 2000 Hyundai Tiburon. When I turn my running lights / head lights on, my brake lights also turn on. Does anyone have any idea what the fix for this might be?

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This is a examin the schematic question.Are you saying when you turn the headlight switch to the running light position the headlights come on at full intensity and the brake lights (not the rear running lights) come on. Is the truck equipped with Daytime Running Lights? No recent accident damage and no recent trips to the mechanic?Does the third brake light come on?.Any recent addition of trailer wiring?

When I turn my light switch to the first position, the running lights turn on, not the head lights. The head lights turn on when I turn the switch to the second position, as they should. However, the issue is that when I turn the light switch to the first position, the right and left (not the 3rd center light) brake lights turn on as well as the running lights. The 3rd light works normally all the time regardless of position of the light switch. When the light switch is in the off position, all the brake lights work normally. No recent work or accident damage.

Start at the rear bulbs. Something is bridging the contacts at the base of one or both bulbs, causing both filaments to light.

Have you changed the bulbs recently? If so, are they the right ones and are they installed properly?

Oldschool: The Tiburon is a sport coupe, not a truck.

You know I am changing my reading material from WW2 airplanes to current automobiles but I have some catching up to do. What site do you regulars use to get such info. Like the post where the guy is asking about a clacking noise in his engine when cold,I can’t answer him because I dont know about his engine design,and HellKit always seems to know about TSB’s and wire colors where is he getting this info?thats why I was asking about ALLDATA.Doesn’t Tiburon sound like a truck name like Rubicon?..Sorry

This could be caused by wires which have gotten too intimate and rubbed each other raw. This could expose the tail light wiring and the brake light wiring to each other electrically, creating a common electrical connection. This can happen in the trunk lid, or lift gate, where the wire bundle flexes (or rubs on something) each time the lid (gate) is opened, or closed.
Open the trunk lid, or lift gate, and examine the wire bundles.

After you turn on the headlights, what happens if you hit the brakes, do they get any brighter? dimmer? go out completely? Have you had this vehicle long? Could it be that someone has put in the older generation LED taillights. They were almost as bright in the taillight position as they were with the brake lights on, it was hard to tell when the brakes were applied.

If the brake lights go out with the headlights on and teh brakes applied, then you have lost the ground connection for the brake/tail lights.

After I turn my running lights on, my right & left brake ligts turn on and stay on as long as my running lights are on. Turning the switch from the running lights position to the healights position does not change anything as far as my brake lights go. The brake lights still stay on. When I hit my brake with my running lights/head lights on, the rear center light tunrs on, its the brake light that is on the spoiler. The left and right brake lights do not turn on or off when I hit the breake while the runnig lights are turned on.

I just bought the car a little while ago, so I did not know the issue. As it turns out, the right rear tail light/brake light had the wrong bulb in it. I put the right bulb in, problem went away. Thanks everyone.

Thanks for coming back with the fix. So, it was the right rear tail light, with wrong bulb, which was bridging the tail light circuit with the brake light circuit…as NYBo postulated.

Could anyone help me???
My rear brake lights stay on when I turn on my headlights I have a 52 plate vauxhall zafira
Thank you

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If you read this 8 year old thread the problem was wrong bulb. Replace all the bulbs at the rear of vehicle. Also this site has mostly U.S. based members so Vauxhall experience is small.

Thank you for your help, I have managed to sort out this issue
Kind regards

I have the same problem with my 2018 Ford F-150 and replaced the bulbs, but the problem persists.

Here’s what I have so far:

When I turn on my headlights, my brake lights come on. I changed out the bulbs on both sides and it still exists. I think it’s in the multi function switch inside the steering column. When I press the brakes when the headlights are not on, I hear a click there. When the headlights are on, I don’t hear the click–just silence. I also seem to hear that same brake light click (inside the steering column) when I turn on the headlights.