My tongue jack only works when connected to shore power or when fully hooked up to truck. I thought the battery might be the problem but had it tested - tested good. Any ideas of where to look?
Check the battery connections on the battery.. Make sure you hit them with a wire brush and re-connect.
Happened to me one time when I was leaving a site. Didn't mess with it at the time and plugging into the truck solved it, but when I got home, trouble shooted it a bit more and after cleaning the connections on the battery, it was all good again..
If I blew a fuse, it would not work at all, correct? I totally removed the battery to have it tested and make sure it was charged. The nuts are clean and tight. I will have to look but I dont recall a ground wire - I think the bolts to the frame may be the ground - not sure though
On my older jack, the ground was thru the bolts to the frame.. That was the jack that didn't work that one time for me.
I've since replaced that jack with a new one (the old one finally just broke in the gear box) and the new one has it's own ground wire directly to the battery.
Dunno what else to suggest since you seem to have a different issue than I did with my old jack.
I had that problem, its a bad ground. make sure where the ground wire is is on bare metal, scrape the paint and use a star washer to help make the ground better,The reason it works connected to the vehicle is the ball is a good ground and when using shore power you are using a different ground. hope they helps.