2025 Ram Trailer Light Issue

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IOWEGN

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My 2025 Ram Laramie tells me I have a trailer light out. When I hook up the lights the turn signals and brake lights are fine but when the running lights come on they blink then shut off. I took my trailer to a shop and all the lights work perfect when hooked to a battery? Anybody else having this issue?
 

CLARKWD

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Same problem here. Its an old trailer with incandesant bulbs. The flat cable has two feeds, one for the left and one for the right side, brown and green and brown and yellow wires. I get lights with either one, but not both.
 

CLARKWD

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Do the two people above and others that are having trouble with the tail lights have trailers with incandesant lights?
Is there anyone with a trailer with LED lights that is having a problem?
 

crash68

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Same problem here. Its an old trailer with incandesant bulbs. The flat cable has two feeds, one for the left and one for the right side, brown and green and brown and yellow wires. I get lights with either one, but not both.
Sounds like grounding problem, the Green and Yellow are the turn signal/brake lights, the brown is the running lights, the frame is ground and goes through typically the white wire. If you can't get both the running and turn signal to work at the same time, check all the grounds including on the truck.
 

KeithP

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Four flat:
Green is right side brake/turn.
Yellow is left side brake/turn.
Brown is tail/marker lights.
White is ground.

Get a four flat light tester. See if the truck works with it. If yes then it’s the trailer. As stated above, most likely a grounding issue.

Typically, a LED lighted vehicle towing a trailer with incandescent lights isn’t a problem. However an incandescent lighted vehicle towing a LED lighted trailer can have issues.
 

crash68

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However an incandescent lighted vehicle towing a LED lighted trailer can have issues.
The Gen4 trucks which were all incandescent lighted didn't care what type of lights are on the trailer. Each of the lighting circuits came straight off a fused relay in the power distribution module.
 

KeithP

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The Gen4 trucks which were all incandescent lighted didn't care what type of lights are on the trailer. Each of the lighting circuits came straight off a fused relay in the power distribution module.
It’s usually older vehicles that have that issue. And at that, not all do. I’ve been with U-Haul for 17 years and counting. I’ve trouble shot more vehicles/trailer wiring issues than I care to think about. It’s usually a very simple fix and overwhelming it’s a grounding issue. It’s just a matter of finding it.
 

Dean2

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Agree with KeithP. Ground on the trailer, or the trailer ground to the vehicle is 90% of the time the cause of these types of issues. You know you are getting power on the circuit, check oat the bulb socket itself..
 

skeeetime

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It's not a grounding issue. My trailer won't light up at all with my new 2025 but every other truck I hook ir up to lights it up just fine. We tried a few other 2025's at the dealership and none of them little up my trailer. Then we tried other trucks on the lot a 2024 and all of thier sued trucks light it up just fine !! I jabe 10 marker lights and 4 taillights that are all incandescent but an that shouldn't matter. I'm told it's a problem with the software on the item and hey are supposedly working on a fix. What Frickig idiot designed something a truck to NOT ight up trailers.
 

Fast69Mopar

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It's not a grounding issue. My trailer won't light up at all with my new 2025 but every other truck I hook ir up to lights it up just fine. We tried a few other 2025's at the dealership and none of them little up my trailer. Then we tried other trucks on the lot a 2024 and all of thier sued trucks light it up just fine !! I jabe 10 marker lights and 4 taillights that are all incandescent but an that shouldn't matter. I'm told it's a problem with the software on the item and hey are supposedly working on a fix. What Frickig idiot designed something a truck to NOT ight up trailers.
What the idiots are doing when designing the software that a truck needs is each year they keep paying so many warranty repairs from customers who hook crap junk trailers to their brand new shiny pickem'-up trucks and they have tried to make the trailer tow circuits so robust to be able to handle every single style of trailer ground, light bulb and dirty resistant wiring they more than likely will have to relax the metrics in the software so that it doesn't see a hazard when the trailer tow circuits goes 1 amp over the rating.

I've been in the dealership for 25 years and I have have been around every single new year and model released since 2000 and each year their are new hurdles but with the trucks and their trailer tow circuits it can be very difficult.

What I would do is ask you to bring your trailer to the shop. The first thing I would do is take your VIN and verify that you have the correct sales code for trailer tow and then verify that all of the trailer tow equipment is installed. I believe the correct sales code is XHC. Then, I would connect the WiTech to your truck and verify wether or not the ITBM even sees your trailer or not.

This could be a very simple programming fix or it could be something that the engineers put in the software that is not allowing the ITBM to see the trailer.
 

skeeetime

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I have taken the trailer and truck into the dealership and they put a plug tester into the truck and said that it was working fine. I had to force them to hook up other trucks and show them that every other truck works other then my 25 and the other 25 they hooked up. It ended with them saying sorry we cant help you we will let you know if Ram comes up with a fix. I buy a new ram every couple years and this is crap. IM just not getting good polite svc and now Ill be borrowing a truck to pull my trailer. And the trailer is all aluminum in very good shape.
 

skeeetime

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The truck does know a trailer has been hooked up . it shows on dash and a trailer light comes on but they dont know what that means lol
 

GTyankee

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Funny that not 1 person has made the statement that their 2025 Ram works perfectly when hooked up to a trailer !!


now that i have mentioned it, we will likely see some trolls
 

newmoonfishing

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New 2025 Ram Rebel here. I just picked up a brand new Kaufman Car Hauler Trailer. Turn signals on the trailer work. Brake lights in the trailer work. Hazzards on the trailer work. Running night lights do not. Plugged the trailer into my son's 2021 F150 everything works, my neighbors 2023 Ram, everything works. My dealer wants me to bring the truck in on Saturday so he can test with a meter. Do we have any service bulletins or any other information that I can provide. On the phone he thinks its a problem with the trailer, I know that it is not.
 

Dean2

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If you want to avoid a lot of wasted time and useless arguement, video the trailer light behaviour on the Ford and the 22 Ram. That proves the trailer is fine. Since most of the lights work on your 2025, it could be the running lamp circuit on the pickup has no power.
 

newmoonfishing

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Ok I wanted to give an update. Dealer was no help with this problem. But it is definitely a voltage issue. Today I swapped all of my trailer lighting from Incandescent to LED and all lights work proper now.
 

tricky rick

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I had the same problem on my 2025 Ram. I had to change the taillights to LED. Everything works like its suppose to. The amperage on the 2025 is too low to allow the incandescent lights to work. Supposedly there is an amperage module that you can order to fix this, but I am yet to find one.
 

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