Trailer brake lights on constant

[coyotefan81]

I have a 53 dry van and the brake lights are constantly on. I can shut off all my lights and the brake lights are still on. I've replaced the electrical cord from the truck to the trailer and I've replaced the 7way on the trailer and still the same issue. Anyone have any suggestions on what it could possibly be? I'm out of ideas.

 

[Johndeere4020]

I have a 53 dry van and the brake lights are constantly on. I can shut off all my lights and the brake lights are still on. I've replaced the electrical cord from the truck to the trailer and I've replaced the 7way on the trailer and still the same issue. Anyone have any suggestions on what it could possibly be? I'm out of ideas.

Brake lights are not usually a trailer problem, if you unhook the pigtail do the tractor brake lights stay on?

 

[Humble pie]

Sounds like the pressure switch on the truck to me. Or at least that’s the first place to look

 

[Duck]

Yeah are the truck brake lights stuck on or just on the trailer?


I'm gonna park this here whether it's needed or not, just cuz everyone should have it. This sticker was on the front of a Great Dane reefer

 

[coyotefan81]

Brake lights are not usually a trailer problem, if you unhook the pigtail do the tractor brake lights stay on?

If I unhook the pigtail then the lights go out on the trailer...all my lights on the tractor continue to work as normal

 

[Johndeere4020]

If I unhook the pigtail then the lights go out on the trailer...all my lights on the tractor continue to work as normal

The tractor brake lights go out when unhooked from the trailer? Do you have a test light?

 

[coyotefan81]

The tractor brake lights go out when unhooked from the trailer? Do you have a test light?

No....my lights on the tractor work as they should....with or without the pigtail plugged in

 

[Johndeere4020]

No....my lights on the tractor work as they should....with or without the pigtail plugged in

No test light?

 

[coyotefan81]

No test light?

I dont have a test light but I'm sure I can get one....what do u want me to test?

 

[Sinister]

Could be just a ground problem.

Spread the prongs inside the trailer portion of the pigtail. Gently. And only a little bit.

 

[coyotefan81]

Could be just a ground problem.

Spread the prongs inside the trailer portion of the pigtail. Gently. And only a little bit.

Even though I just replaced that unit?

 

[Johndeere4020]

I dont have a test light but I'm sure I can get one....what do u want me to test?

You need to figure out where the problem is, test the bottom prong in the seven way at the back of the tractor.

 

[Johndeere4020]

Could be just a ground problem.

Spread the prongs inside the trailer portion of the pigtail. Gently. And only a little bit.

A ground issue is not going to cause the brake lights to stay on

 

[Sinister]

Even though I just replaced that unit?

Sure. They’re slapped together in a hurry just like anything else.

also, electrical grease will help prevent corrosion and increase conductivity without bursting into flame...

...as fun as that is to watch...

 

[Johndeere4020]

Even though I just replaced that unit?

That’s not the problem.

 

[Sinister]

That’s not the problem.

Perhaps not, but when troubleshooting you start with the simplest solution and get more aggravated from there.

 

[Johndeere4020]

Perhaps not, but when troubleshooting you start with the simplest solution and get more aggravated from there.

Yes but if the brake light is stuck on then ground isn’t our issue so that’s a waste of time. The first thing you have to do is find the root of the problem, start at the tractor

 

[Sinister]

Yes but if the brake light is stuck on then ground isn’t our issue so that’s a waste of time. The first thing you have to do is find the root of the problem, start at the tractor

You think maybe it’s the pigtail on the tractor?

My other idea was a blown fuse or relay.

 

[coyotefan81]

You think maybe it’s the pigtail on the tractor?

My other idea was a blown fuse or relay.

I've checked the fuses and they all seem fine...I'll check them again...maybe I overlooked something

 

[Duck]

Is it possible you got the blue and the red wires switched with each other? Refer to the photo I posted