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Brake lights and hazard quit working

Tiny
ASEMASTER6371
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This is at the rear of the truck? You never mentioned that at all.

Was there a cap on the back of the truck at some point?

Roy
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Monday, December 28th, 2020 AT 3:24 PM
Tiny
DANOC22
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You saw it in the picture of the connector. Cap you mean like a camper type cover? I have only had the truck 2 years. It has a trailer harness.
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Monday, December 28th, 2020 AT 3:31 PM
Tiny
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Okay, at this point you need a shop that is good at electrical work. You have a harness issue somewhere that was modified or changed by someone and needs to be traced to find out why you do not have rear brake lights.

Roy
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Monday, December 28th, 2020 AT 3:42 PM
Tiny
DANOC22
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I had them they just quit. I do appreciate your time. Thanks Roy and everyone that helps. Dan
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Monday, December 28th, 2020 AT 3:54 PM
Tiny
DANNY L
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Hello again.

I caught this post toward the end of the repair. What was fixed and what still is the issue and needs to be repaired? Just want to be on the same page. Thanks again for using 2CarPros and Happy Holidays.

Danny-
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Wednesday, December 30th, 2020 AT 5:08 PM
Tiny
DANOC22
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I don't have the always hot wire at the brake light relay fuse box under the hood. Replaced the brake switch the multi switch. I took the white wire that tested hot when the brake on. I spliced it into my brake wire and now have brake light and two hot in the relay box with the brake on. But lose my right turn signal. I did take those two wires apart. I just wanted see if it would tell me anything. Bottom line my brake light on the cab works all light work but tail brake light.
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Wednesday, December 30th, 2020 AT 7:00 PM
Tiny
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Going back to the start, do you have power out of the multifunction switch to the wires to the rear tail lights with the brake pedal depressed?

Roy
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Wednesday, December 30th, 2020 AT 7:06 PM
Tiny
DANOC22
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Yes.
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Wednesday, December 30th, 2020 AT 7:17 PM
Tiny
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Okay, if you have power out of the switch, then it is wiring to the rear lights. It is a direct path to the rear sockets.

Did you test for power to the rear sockets?

Roy
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Wednesday, December 30th, 2020 AT 7:23 PM
Tiny
DANOC22
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All lights work. The brake lights work. I wired them to my cab brake light they work then.
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Wednesday, December 30th, 2020 AT 7:27 PM
Tiny
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What happens when you use the turn signals?

Roy
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Wednesday, December 30th, 2020 AT 7:31 PM
Tiny
DANOC22
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All lights work exactly the way they should, not the brake light.
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Wednesday, December 30th, 2020 AT 7:33 PM
Tiny
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In the brake relay wiring is one wire hot all the time?
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Wednesday, December 30th, 2020 AT 7:35 PM
Tiny
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They should not if you went around by tying into the 3rd light.

Going back to the diagram, there is a fuse that supplies power all the time to the relay. The white wire feeds it only after the pedal is depressed.

Check the diagram I posted in the beginning.

Roy
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Wednesday, December 30th, 2020 AT 7:42 PM
Tiny
DANOC22
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That fuse is good. So the cab light does not go through the relay?
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Wednesday, December 30th, 2020 AT 7:47 PM
Tiny
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No, if you look at the diagram, it comes from the brake light switch white wire.

Roy
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Wednesday, December 30th, 2020 AT 7:53 PM
Tiny
DANOC22
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That's the one that hangs down in the picture at rear from the harness. Is that right?
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Wednesday, December 30th, 2020 AT 7:58 PM
Tiny
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No, this is all from the front by the brake light switch. That wire was added by someone for some reason.

Roy
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Wednesday, December 30th, 2020 AT 8:01 PM
Tiny
DANOC22
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There is a surge brake in it.
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Wednesday, December 30th, 2020 AT 8:06 PM
Tiny
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Surge brake is like a master cylinder that activates the trailer brakes.

The only electricity you have for the trailer is the lights. That is the white wire at the back that you have hanging free.

Roy
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Wednesday, December 30th, 2020 AT 8:11 PM

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