Update to Friend's 5th Wheel battery problem

[akadeadeye]

Many thanks to all the replies about my other post concerning a friend's problem with his pickup truck not charging his trailer battery.

Here is an update and I would like to ask if anyone has knowledge about this problem.

He told me the 7 pin plug on his Ford F350 diesel, with a towing package, is the culprit. It is a factory plug. Apparently, the 7th pin (the one in the center) is the one meant to charge the battery, but it is wired to service the backup lights instead. So, the only time his trailer battery is being charged by his truck battery is when he is backing up.

Any thoughts?

Thank you

[TXiceman]

Thanks for checking back on the problem. It is always great to hear the solution.

I will have to go and check mine now.

Ken

[RustyJC]

The center pin (#7) is used for backup lights. #4 pin is the battery +12VDC charging circuit.

It sounds like your friend needs to fix the wiring on the trailer side, not the truck side. The 7 flat pin connector wiring schematic is shown HERE for both the truck and trailer sides. Wire the pins according to function, not according to wire color (which can, and probably will, vary).

Rusty

[Superslif]

Thanx
Rusty for the link to the wiring diagram. I'll keep it handy for the future.....