03 Trailer Wiring Diagram
 

My truck has a factory plug on it with the rectangular plug that plugs into the back of the trailer plug. I'm not positive which wire coming out of the back of the plug is the right turn wire. I do not have right turn signals on the trailer. I tried tracing the wires but someone has cut into the harness at some point and I can't follow the wires back.

Any help/ diagrams or a direction I can find a diagram would be great!

I googled the custom wire harness for a 2003 Dodge Ram 2500 (hope that is correct.)

Looking at the picture, it appears it should be on the upper left looking at the rectangular plug with the mating face away from you. It should be the green wire in this picture.

I think.....does this help?

https://www.etrailer.com/static/imag...55381_1000.jpg

https://www.etrailer.com/static/imag...55381_1000.jpg

I can't remember the colors coming out of the plug whether they match these colors or not. But knowing which pin it is is very helpful. I can trace that wire from there.

I am also looking for the wiring that may come from the front of the truck, too. These colors don't match the factory harness from the adapter plug shown in your picture.

Thanks.

The colors won't match. I was just hoping form the pic it would point you to the correct pin in the plug. Turn your signal on and stick a test lamp probe in it.

I just went through this very thing. The 03-05 trucks have relays in the PDM (fuse box) that control your left, right and driving lights. The relays go bad. Couple years ago I split the fuse box open and replaced the 3 relays with the 30 amp Zetter relays. Problem solved, for a while.

Within the last year I have been having intermittent issues with my right trailer turn/brake light. When you have your turn signal on, take the cover off your fuse box and listen. If you hear clicking from the fuse box you either have a bad contactors in the relay, or a broken wire. Most likely you will hear nothing. If that is the case check fuse #46. If the fuse is good then you may have a bad relay, PDM or FCM. In my case it turned out to be the FCM acting up.

One of the most stupid designs I have ever seen.

I finally got fed up with it and installed one of these and remove the trailer light function from the PDM altogether.

https://www.napaonline.com/en/p/TWR48000



If you are trying to check for voltage at the plug on the rear bumper, the factory wire colors on my 04 were yellow (left turn/brake) green (right turn/brake) and brown (driving lights). I was amazed Chrysler used these colors.

Here is a picture of the relays in the PDM.

https://uploads.tapatalk-cdn.com/201...567f5b15d9.jpg

https://uploads.tapatalk-cdn.com/201...481f349353.jpg


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Agreed. Completely.

So I was wrong it is my left turn signal that does not work. Anyway...

When the right turn is on I hear the clicking under the fuse box under the hood. Left turn I hear nothing. How do I get to these relays? Do I have to pull the box and split it in half?


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Yes. You have to pull the PDM from the truck. You have to remove all the fuses, relays and FCM mounted on the side. Then you have to drill the 3 weld points inside the box and separate the components like I had pictured above. You have to be really careful and patient. It is easy to break. Then you have to desolder the 3 relays and replace them with the 30 amp Zetter relays. I don't have the part numbers anymore but there are a lot of articles and videos on this subject that will give them.


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Thanks for your help! Sounds like I'm better off spending the money on a new fuse box....


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How's that? What do you have to lose? $500-$600?

Most likely the PDM is the issue. In my case the first time it was the PDM (fuse box). The second time it was the FCM. Both are vehicle specific so if you buy a new one get the identification off the one you currently have.

This is the identification number off the one in my truck.

https://uploads.tapatalk-cdn.com/201...0cd56b330f.jpg

After I narrowed it down to the FCM I was pretty disgusted with the whole design.

The kit from Napa was $80.00 and the problem is solved and much better.

https://uploads.tapatalk-cdn.com/201...974d76c6a5.jpg

It is a little frustrating to deal with the stupid wiring under the rear bumper but in the end it was worth it. I have a lot of extra stuff going on with a rear camera and reverse lights.

https://uploads.tapatalk-cdn.com/201...3b6533e2b6.jpg

I wanted to make this much cleaner but I didn't have time right now. Just wanted to get it working.

I will come back to it.
You can see the Napa module mounted above the frame.

https://uploads.tapatalk-cdn.com/201...39cf1c075a.jpg

I have a "Line of Fire tied to my trailer lights so I know they are working even if I don't have a trailer connected.


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I chose to solder and shrink tube all the connections instead of using the wire taps they provide. I don't trust those things long term.

So the NAPA solution ties into the factory tail light harness correct? This may be the route I go. I am nervous about pulling the fuse box apart.

That is correct. If you look at Google images for the rear taillight wiring diagram it gives the color codes on some of the drawings for the wires. You may need a magnifying glass to read the codes but they are there. I test the wires with a meter before I spliced them. I had to put my Daughter in the truck and raise her up on the lift. LOL! She didn't like it very much.

The kit is designed to mount behind the left rear taillight and pull the stop signal, left turn signal and driving light signal from the left side tail light. The kit then has a longer wire that runs to the right side tail light for the right side blinker. I just went straight to the left side frame rail where all the wires for the lights are located and went from there. After that you just cut the yellow, green and brown wires going to the trailer plug harness and connect the trailer plug to the same color wires on the kit.

You will also need to connect a ground and runt a wire up to the battery with a fuse. It isn't as easy as changing the fuse box but it is much cheaper and IMHO much more reliable.

I also pulled fuse #46 and #47 after I did this so the wires I cut are not live if the fuse box magically started to work again.:bang

Thanks for posting all of this. My driving lights apparently decided to not work the other night. This will give me a good starting point.

Thanks again! I'm not really a fan of splicing in to the factory wiring harness, but if it is cheaper, easier and more reliable in the long run I guess I will do it. I will be soldering and shrink tubing all of the connections as well. I've used butt connectors to many times and had them come apart or corrosion get into them and have to redo it. Never had any problems soldering!

How do you work the trailer brake wiring and brake controller into this? Or does it still work through the factory wirign?

I am still using the factory wiring for everything else. The full time power, brakes and reverse are working fine. I did keep the ground hooked up and just spliced the white ground wire from the new adapter into the factory wire.

Started on this, this past weekend. Really wasn't a terrible job. Took me about an hour and a half to get the 4 way plug wired up. I soldered all of the connections, because I didn't want to have any trouble. If I wire the power wire from the battery to the convert box to a toggle switch, will I have an interrupt?

I'm still having trouble figuring out the factory connector and what prongs go to which operation. Having one light out doesn't help identify which wire it belongs to. My dads 05 seems to be wired differently. I tried checking his plug against mine but it seemed all off.