Fuse blown in reverse.

[beezee28]

I have a dodge 1500 as my tow vehicle and the fuse for the reserve light keeps blowing when I have the trailer hitched on. That is when I reverse to put the boat into the water, fuse is burned. I checked the ground connection on the 4 flat and it is good. I checked the wire on the trailer and it is good. All the connections on the trailer are soldered not twisted, so the connection are solid. Look on other thread on this but cannot find any. I have to replace new fuse or have to take out the fuse before backing the trailer into the water. The fuse is rated 10A. Any idea what is wrong??

 

[MTboatguy]

Re: Fuse blown in reverse.

There is only ONE reason a fuse blows like that, and it is because you have a short somewhere, either by incorrect wiring, or something in the truck is shorting out, but there is a bare hot wire grounded to metal somewhere in your set up, or the ground is wired to a hot lead..

Keep checking, you will find it...

Of course, by the time you find it, you might be bald from pulling your hair out!

 

[64osby]

Re: Fuse blown in reverse.

I agree w/ MTboatguy

Hook the trailer up to a different vehicle. If it blows, its in the trailer, if not it's in the Dodge. Bring a spare fuse for your friend.

 

[dockwrecker]

Re: Fuse blown in reverse.

Have a look at the wiring from your harness to the 4 flat on the truck side. Reverse shouldn't be wired to a 4 flat. Is it factory wired? Are you using a 7 pin to 4 adapter? It almost sounds like the reverse lights got wired to the white wire on the 4 flat. So when the trailer is hooked up, the reverse lights are instantly grounded.

 

[Silvertip]

Re: Fuse blown in reverse.

Most trailers don't have back up (reversing) lights so that circuit on the truck should not be wired into the trailer harness. The four wires are left turn, right turn, tail (running) and ground. Four wires only. Back up lights would make five. Check the wiring on your trucks harness. The problem is with the truck -- not the trailer.

However, if the trailer has surge brakes with a reverse lockout solenod, then there would be a fifth wire in the trailer harness and there could be problem with the trailer wiring or the lockout solenoid.

 

[mike343]

Re: Fuse blown in reverse.

As above, the four pin connector should not have the reverse/back-up wire connected. If you have a blue wire on the truck side, disconnect it. Post says fuse blows when backing up to launch. Does it blow when backing up not on the ramp?

 

[Josh P]

Re: Fuse blown in reverse.

my old dodge did the same thing, the white wire on the truck side is the reverse power. . to double check put the truck in reverse and have someone hold the brakes. using a test light stick the probe into the white wire terminal end and it willl most likely like up, just cut the wire, but connect a longer wire and hook it to a good grounding spot on your frame. let us know. thats what happened to me after i installed the aftermarket truck side"plug n play" tee wiring harnesses
*edit* just reread your post..you have ground and you will untill a power is applied to that wire... trust me disconnect your trailer have some one hold the brakes and put it in reverse(with key on, or vehicle running), you prob have power on your white wire.

 

[DianneB]

Re: Fuse blown in reverse.

I had exactly that problem with my Jeep and it took me ages to track down that the dealer-installed trailer package had tapped the trailer ground into the backup light circuit (dark brown) instead of the vehicle ground (black). When the vehicle was in reverse, any time the ball/coupler made good connection, it would blow the fuse.

 

[gstanton]

Re: Fuse blown in reverse.

Also, some trailers have a solenoid that is activated by the reverse lights of the tow vehicle. This solenoid locks out the hydraulic brakes on the trailer, allowing it to back up.
As others have said, this is not the situation on a 4 or 5 wire plug, only on a 7 pin round. The center pin should be the "Reverse" hot wire.

Is it possible that someone wired the trailer for this solenoid, but the tow vehicle isn't?