2015 ram 3500 right side trailer blinker/brake doesn’t work, but right side running light does work when headlights are on

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pitcherofnectar

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It’s not the trailer, because this happens on every trailer I have. The right turn signal/right brake light doesn’t work on any trailer I connect, but when I turn on the truck’s headlights the low intensity red running light on the right side of the trailers does illuminate. On the truck, the right side light works totally fine, brake, turn signal and running lights all as normal. I have replaced the trailer connector on the truck, both the 4 pin and the 7 way sockets. No luck.

Do I need a new TIPM? New wiring harness? Hunt down the fault in the brake/turn wire and fix it? I know the harness has 3 sections with plugs in different parts of the truck but I can’t find which one has the fault or if it’s the TIPM itself not sending a signal. The fuse looks good
 

Burla

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The truck is fine, I doubt it is TIPM. I'd try and use one of those cheap led lights and wire it to the wires going to brake light if it were me. Those cheap leds provide you a blinker and constant solid red, I do believe that would qualify as road legal but I'm not 100 on that. Sounds like maybe the wire from bumper connector to tipm is messed up?

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pitcherofnectar

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The truck is fine, I doubt it is TIPM. I'd try and use one of those cheap led lights and wire it to the wires going to brake light if it were me. Those cheap leds provide you a blinker and constant solid red, I do believe that would qualify as road legal but I'm not 100 on that. Sounds like maybe the wire from bumper connector to tipm is messed up?

I been Jerry rigging it for years, I want to actually fix the problem now. I do think there is a break in that line between the connector and the TIPM, and I want to find it and fix it, but my tech is telling me going down that road digging into the harness could cause more problems along the way. Does anyone know or have a diagram on the wiring harness showing what color wire this one would be? Or which hole I can test it on the mid-harness connectors?
 

mtnrider

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Have you checked the fuse? The right turn/brake are on the same fuse and separate from the truck (on the 4 pin).

Also, the 4 and 7 pin connections are completely different circuits in the truck. Are you saying neither work? If so I would look hard at the trailer again because the odds of both those circuits having the exact same issue is pretty rare

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Burla

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If a ground on the trailer was bad it could have blown a fuse, maybe even damaged TIPM now I think about it, this happened to my truck. I was just going to jerry rig it though, it is just a landscape trailer and I don't tow much to replace stuff. Good luck

Point being, if it was a trailer short that caused the damage and you didnt fix the trailer short, then you hook that trailer up again after fixing your truck, it will cause damage again.
 
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pitcherofnectar

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Have you checked the fuse? The right turn/brake are on the same fuse and separate from the truck (on the 4 pin).

Also, the 4 and 7 pin connections are completely different circuits in the truck. Are you saying neither work? If so I would look hard at the trailer again because the odds of both those circuits having the exact same issue is pretty rare

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I will double check 4 vs 7 pins later today but it happens on all 3 trailers I own, and all three work perfectly normal on my wife’s jeep. Fuse looked fine and I was getting a flasher signal on a circuit tester from where the fuse goes, but I will replace it and see. Just wondering about the harness connection plugs under the chassis, if anyone knows which wire is the right trailer flasher and if so where it is located in that giant plug
 

mtnrider

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I will double check 4 vs 7 pins later today but it happens on all 3 trailers I own, and all three work perfectly normal on my wife’s jeep. Fuse looked fine and I was getting a flasher signal on a circuit tester from where the fuse goes, but I will replace it and see. Just wondering about the harness connection plugs under the chassis, if anyone knows which wire is the right trailer flasher and if so where it is located in that giant plug

I may have mis-spoken on them being separate, they may actually be tied together. Here is the pinout for the 7 pin..


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