12V Meltdown on battery charge wire

[vrrogers]

On last trip out with 2007 3000RK had a major event happen when hooking up umbilical cord to tow vehicle. Even though plug and receptacle are keyed to prevent incorect insertion it is possible to insert incorrectly. This placed the + side of battery in 5th wheel directly to ground of tow truck. Apparently there is no safety device in the 5th wheel ie, fuse or fusible link on the battery charge wire to prevent a meltdown. The battery charge wire turned red hot, melted all the insulation on that wire and melted several other wires in the bundle as well. This also placed the 12V truck battery to ground but a 40 amp fuse in the truck fuse panel opened so no damage to truck. Repairs are estimated at approx. 1K. I will be adding a fuse to this battery charge line to prevent it from ever happening again. Has this happened to anyone else?

[cooneck]

Yes, it happen to me today. I don't know if I put the umbilical cord in back-wards but the wire harness from the pin box into the the camper melted the insualtion on the wiring. It could possibly be that I did put it in upside down or there is an open ground somewhere. Will be calling to have it towed and repaired.

[ols1932]

I looked at mine and I can't see how it would be possible to put it in wrong. It has a large keyway and won't go in unless the key on the cord matches with the keyway on the plug on the tow vehicle. Are there different cables and plugs out there?

Orv

[cooneck]

You're right Orv I just checked it out and it will not fit if the key is not right side up. Something else must be shorted out. I'll find out when the service people look at it. Cooneck

[vrrogers]

I didn't believe that it could be inserted the wrong way either until I saw it with my own eyes. The receptacle in the truck was one I had installed at the same time the super slide hitch was installed. The opening diameter was just large enough that you could accidentally insert the connector in upside down. The dealer has now installed a better fitting receptacle that should preclude it from happening again. One other note is that the technician that repaired it told me he had also seen meltdowns caused by owners who coil up their umbilical cord after unhooking and placing the coiled up cord inside the pin box. Since there is always 12DC from the 5th wheel battery charge line present on one of the terminals all it takes is for that terminal to contact ground anywhere, i.e. a screw or any metal surface. It would be good practice to wrap the exposed end of the umbilical cord with electrical tape or some other insulator if you plan to tuck it away in the pin box.

[richfaa]

This is exactly what happened to us in Quartzsite winter of 06 and caused our meltdown. Had nothing to do with the truck .The charge wire shorted to the frame of the Montana and melted a hydraulic line which burst into flame.Everything in the pin box bundle was melted.We were lucky that we were not hooked to the truck at the time or there would have been much more damage. Damage was confined to the 3400 and it was repaired at Keystones expense.

[HamRad]

I would have to work all day to get my cord plugged in the wrong way! If the process I was using had it so that you could plug it in wrong and burn out all kinds of things I'd change it!

And the same goes for coiling up the cord and putting it up in the pin box. It would take and extraordinary coincidence to hit something up there that would short out. I find that it would be almost impossible. Of course weird things can and do happen so I won't rule it out completely.

A wire getting cut and shorting out..... well now that is much more likely to happen. Just check from time to time to make sure everything is as it should be and you should be safe.

HamRad

[bsmeaton]

I've done it. The plug doesn't have to go in, it just has to make contact with a spade on the receptacle and at least on mine they can touch by tilting the plug. It only takes the one to touch, because you're already grounded to the trailer. Mine happened while fumbling in the blind over the edge of the fender trying to hook up. I heard it pop and crackle, but all I got was arc marks on the plug. I now guide it in with my finger on the top key.

I can't remember for sure, but I think this 2007 has a cheesier plug than our 2003 had. I don't remember ever having that problem on the old one.

[Trailer Trash 2]

I remember a few years back when this happened the wires that go through the wall to the power supply rubbed the steel and shorted out the battery, I believe Keystone put a insolator gromet to stop this from happining again, a piesce of rubber hose cut down the length to incert it over the steel hole should help for a quick fix.

[jjackflash]

Mine trailer plug has a blue dot on top,it seems impossible to plug in upside down but I guess not.
Jack