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HiTechRedneck

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Discussion starter · #1 ·
Need some help. No power at 4 pin connection, or 7 pin connection mounted in bumper. Checked all fuses and all bulbs on trailer. Truck lights work fine. Is there a hidded fuse, or relay some where that would cause this? Thanks in advance.
 
Discussion starter · #2 ·
Need some help. No power at 4 pin connection, or 7 pin connection mounted in bumper. Checked all fuses and all bulbs on trailer. Truck lights work fine. Is there a hidded fuse, or relay some where that would cause this? Thanks in advance.
 
I am looking at wire diagram. No 4 is for charging, which should have power. No 7 is for auxiliary or back up lights, which most TT don't have. Unless you have back up lights on your TT, I would not be too concerned with No. 7. If No.4 is dead, follow the thick black wire from the bumper connector and look at each place of connector in your truck wire harness from back to front. There should be some kind of big fuse or circut breaker for this one. If your truck was prewired for tow package, look in your fuse panel under the hood. At this time, I do not know which fuse it. If I get a chance, after it stops raining, I can check that for you.
I tried to download a pic for you, but won't let me. Just Google trailer connector and you will find many pics of how it is wired and help you find your issue.
 
had the same problem. put in a whole different circuit...for the electrical. or get it flashed.. which is a little pricey. but mine started working as soon as the circuit board was switched. Its the years of trucks. 03 and 04 have major wiring/electrical problems

this seems to be a pretty common problem amongst people I know with the same year as mine.
 
Discussion starter · #5 ·
EdRamHemi, When I said 4 pin and 7 pin I was talking about the different type of trailer wiring connection. I have chaecked all of the fuses in the fuse panel under the hood. All are good. I have no power at either trailer connection. Looked at wiring diagrams for factory installed trailer lights wiring, and seems it could be the relays in the FCM module. Thanks for the input though.
 
had the same problem. put in a whole different circuit...for the electrical. or get it flashed.. which is a little pricey. but mine started working as soon as the circuit board was switched. Its the years of trucks. 03 and 04 have major wiring/electrical problems

this seems to be a pretty common problem amongst people I know with the same year as mine.
Hello, "BigMeanHEMI" I have an 04 1500 2wd 5.7, my tow lights haven't worked for several years now, I tried changing the whole fuse box with an 05, my tow lights started working but other things stopped working, like elect. Lock, radio, and a couple other things.

Anyway, so how do you change the circuit? Do you mean the FCM?

Just a note about Fuse Boxes, I've also bought 2 Boxes from LKQ, one was an 02 and the other was an 04, but the 2 small harness plugs on the bottom were long oval or rectangle, but the 2 small plugs on my factory 04 box are square!?? 05s are square also.
Any thoughts on this?
 
I didn't leave the 05 box in, I have my factory box in it, factory tow package, but only have park lights, no turn or brake lights. I talked to a 40 year Dodge Mech. and he had me check the line back, and test a couple wires from the fuse box harness, and he said it was in the box. Yet the only box I've found so far that matches my harnesses is an 05, which did fix the tow lights but other things would not work with the 05 box.

I bought my truck when it was 8 months old, box was not changed previously. Harnesses are original. Not sure what to do at this point!?

I really need my tow lights working!
 
This is deff weird. Is it possible that a fuse is not in one of the other boxes causing the issue after that swap? Without seeing this first hand may be difficult to actually know what's going on.
 
This is deff weird. Is it possible that a fuse is not in one of the other boxes causing the issue after that swap? Without seeing this first hand may be difficult to actually know what's going on.
Okay, now in all fairness, as I did check all the fuses in both boxes, I did not test all the relays in the 05 box. I guess maybe I could do that just to cover all the bases. But the other 02 & 04 boxes wouldn't even plug into my small harnesses. So I returned both of them.

Thanks for trying to help Charged392!

Go to my profile and look in "My Truck issues" image folder.
 
This fix works incredibly well. The hardest part was finding the relays. I ended up buying from a manufacturer that had a minimum order of 50, so I bought 50. They were identical except that they were rated at 30 amps instead of the factory 20 amps. I took 3 of them and repaired my own fuse-box 3 years ago. It's still working perfectly now and I tow my boat trailer every week during boating season. The remainder I sold on ebay. I even bought a few "broken" fuse-boxes and fixed them and then sold them on ebay. It was fun fixing them TBH.
 
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