2018 RAM 2500 Laramie - Tail Light Wiring?

[SSLandYacht]

On my 2018 RAM 2500 Laramie, I had installed a CM flatbed, and they didn't know what they were doing.

They cut the plugs off my OEM LED tail lights and wired everything up.

All lights work, but the truck shows right and left turn signals, and the license plate lights are out.

Given that the plate lights were incandescent,t those will need resistors.

Still, my main thing is they didn't delete any of the old harnesses and wires, just sort of "wired all together" stop and turns, and I believe on the 4th Gens, the brake wires and turn signals have to be separated, or else it's gonna read bulb out.

So I'm assuming I need to separate the turn signal wires from their own light and brake wires from their light, correct?

Also, by any chance, does anyone know the color codes for the factory LED tails?

The wires are yellow, green, black, and red.

I've looked online, but there are many dead-end forums where no one explains anything.

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[watersupply189]

I would take the truck right back and make them fix their screw ups.
Hopefully someone here will post a diagram for you.


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[AK Bob]

I can post the OEM wiring diagram for the tail lights on my 2014 3500 premium lighting, but the wire colors don’t match your description.

You may want to consider a subscription to Alldata DIY for your 2018.

https://www.alldata.com/diy-us/en

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[BrentM]

I have the LED tail lights.

After the connector, the wires change colors if I remember correctly.

They are installed in my 2020 Tradesman, but I can get a picture tonight when I get home, and it might make sense.

Do you have separate brake and turn signal lights on your flatbed?

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[SSLandYacht]

Yeah, the factory LED tail lights are two separate circuits: turn and brake.

They have them all wired into the brake circuit like a trailer.

I returned to them and was told that's how it's done: if you don't like it, do it yourself next time.

Yeah, I'm gonna have to if I want it done right.

Also, finding the bed bolts had loose gaps at the rear of the frame where plates needed to be added and all kinds of stuff.

I told them I would need some money back to fix this if you don't honor their work.

I was told to lawyer up if I want a penny from them, and if anyone wants to know who they are here in CA, it's Big Tex Trailer World.

They are not getting any work from me.

I'm consulting my lawyer and firing up a lawsuit to have my truck's wiring harness replaced and do the wiring myself.

If this place always puts flatbeds on, you would think they know how to wire stuff right.

Gonna get on all the data and pull up the diagrams.

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[SSLandYacht]

So the CM skirted bed has 3 lights on each side on the back 2 reds one clear for reverse lights, and up top on rack 1 brake 1 reverse.

Since they have all lights for brake and turn wires together, I was gonna break their harness up to turn and reverse up top and down below to make the outer light a turn and the inner a brake.

Just so many damn lights on this thing, LOL.

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[BrentM]

Here is what I have on my 2020 truck to 2017 lights

Truck > 2020 connector > 2017 Light
BLK > BLK - Two wires, one for backup and one for turn/brake
WHT/YEL > YEL > GRN
WHT/GRN > RED > GRN *
WHT/OR > WHT > YEL
WHT/BR > GRN > PUR
The red wire on the light is not connected to anything
* WHT/YEL and WHT/GR both connect to the green wire on the light

Here are a couple of pictures:

PXL_20250114_045129084.jpg

PXL_20250114_044217927.jpg

The Alldata wiring diagrams for my 2017 don't match the 2020 truck, so ignore that.

But on the light, the green wire is the brake/turn signal, purple is the backup light, and the yellow should be the tail light

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[BrentM]

The red wire is the fault sense wire.

To tell when the light is out.

Mine works fine without being connected and without messages, but that may be your issue.

If everything is working right, you may want to look into AlphaOBD to see if you can change this.

I changed the LED Tail, Turn, and Stop lamps from No to Yes, but you should already have that set with the Laramie tails.

What did they connect the red wire to?

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[SSLandYacht]

Ok, yeah, after messing around with the wiring, the truck was outsmarting me at every turn, so I got AlphaOBD and turned off the rear lighting montoring, LOL easy fix.

As soon as I got my flatbed all outfitted and wiring/lights figured out, I went on a road trip with me 30-foot camper and trans decided to leave the chat.

I pulled the trans and rebuilt it myself.

Wow, 68RFE from the factory are BS LOL, so many cut corners in them.

The seals and bearings are trash.

TQ was a mess after I opened it up.

I ordered the RevMax stage 4 kit with there converter this thing now reminds me of a Ford 5R110 the way it shifts.

I was gonna go the extra mile by figuring out how to add clutches to the 5th and 6th, but I needed my truck up and running, but I have a spare 68RFE now to play with and modify.

The original trans died at 163k with no signs of wear, and CVI numbers were cherry.

My guess is the TQ just gave up and peppered the rest of the trans with metal.

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