I went to pickup my camper today and the electric trailer jack was not working. I assumed I had a dead battery so I hooked up the umbilical cord to the tow vehicle and tried again with the engine running. Nothing. I flipped all the breakers, checked fuses and everything looked fine but I was not getting any power any where. I wasn't even getting a dim light from any of the lights.I thought I had an electrical problem so I got the manual crank out and hooked up the camper. Before I left the storage lot I checked the lights again and to my surprise, they were now working.So here is my question, I thought once you hooked up the camper to the tow vehicle with the umbilical cord, as long as the engine was running, then at least the lights would work. But, I was getting nothing at first. I thought the lights would work even without a battery in this situation?? Not sure if it is relevant, but I did not have the trailer connected to the hitch when the lights were not working at first. Don't some trailers needs the hitch hooked up to establish a ground connect?? I only recall this on smaller flatbed trailers that only have the 3 wire connection and did not think it applied in my situation.So why was nothing working at first? Was the batter just so dead it needed 5 minutes to get a minimal charge? Or do I possibly have an electrical problem that will show up again?

IF the 7 pin is wired correctly. You do not need to be on the ball to power the TT. If not. then the ground was made when you hooked. You should for sure get that checked, as eventually the lights will begin to flash on, and off as you drive.

What is the measured voltage of your depleted battery? It's quite possible that the battery was completely discharged to the point that the small charge current from the vehicle could not power any 12 V devices. BTW, discharge one of those cheap Marine hybrid batteries like that a few more times and your battery will be DOA.

In the future to avoid this disconnect the battery when you put the unit in storage....

You need to have somone electricly savvy check out your system. Too many conflicting symptoms for this to be a single-point issue.

Trailer battery was sucking up everything that little charge line thru 7 pin could supply........5 minutes later battery had a minimal surface charge that lights could work.

Really dead battery?? | Good Sam Community

mfoster711
Explorer II
Sep 14, 2015
Terryallan wrote:

I read it as 'inside lights'
You read it as 'running lights'

Hey OP.....which lights? :B

I was talking about the inside lights. I try turning them on just to see if they will come on even if they are just a slight dim.

I don't know about the outside lights, didn't check that until I was pulling away and they were fine.
Terryallan
Explorer II
Sep 14, 2015
Old-Biscuit wrote:
opnspaces wrote:
The lights are separate from the battery so that parts sounds like a grounding problem with the tow vehicle. I'm betting your umbilical ground isn't working. It's an easy check, chock the trailer tires and turn on the truck lights. Now use the tongue jack to lift the tongue off the ball and see if the lights go out. Or if you don't want to use the tongue jack just hook the umbilical and use a jumper cable to ground the trailer to the tow vehicle.

As far as the battery being dead it sounds like your disconnect didn't disconnect and you had a dead battery. The tow vehicle running for a few minutes finally put enough charge into the battery to get the jack working.

I read it as 'inside lights'
You read it as 'running lights'

Hey OP.....which lights? :B

I read it as ALL lights would not work. However as long as the battery completes the circuit. All lights should work when hooked to the 7 pin, even with a graveyard dead battery. On some trailers, they work when hooked, even without a battery installed.
Old-Biscuit
Explorer III
Sep 14, 2015
opnspaces wrote:
The lights are separate from the battery so that parts sounds like a grounding problem with the tow vehicle. I'm betting your umbilical ground isn't working. It's an easy check, chock the trailer tires and turn on the truck lights. Now use the tongue jack to lift the tongue off the ball and see if the lights go out. Or if you don't want to use the tongue jack just hook the umbilical and use a jumper cable to ground the trailer to the tow vehicle.

As far as the battery being dead it sounds like your disconnect didn't disconnect and you had a dead battery. The tow vehicle running for a few minutes finally put enough charge into the battery to get the jack working.

I read it as 'inside lights'
You read it as 'running lights'

Hey OP.....which lights? :B
opnspaces
Navigator II
Sep 14, 2015
The lights are separate from the battery so that parts sounds like a grounding problem with the tow vehicle. I'm betting your umbilical ground isn't working. It's an easy check, chock the trailer tires and turn on the truck lights. Now use the tongue jack to lift the tongue off the ball and see if the lights go out. Or if you don't want to use the tongue jack just hook the umbilical and use a jumper cable to ground the trailer to the tow vehicle.

As far as the battery being dead it sounds like your disconnect didn't disconnect and you had a dead battery. The tow vehicle running for a few minutes finally put enough charge into the battery to get the jack working.
BFL13
Explorer II
Sep 13, 2015
The trailer 12v stuff will work without a battery on board if you are plugged in so the converter will run the 12v stuff. The OP was not plugged into 120v shore power.

The 7-pin should run everything when the Ford truck engine is running. (It will run with a Chev even if the engine is not running. Not a clue about a Dodge.)

So why did it work later, but not at first?

A. You have a poor connection in the 7-pin and moving the rig wiggled it to make it work.

B. Maybe that grounding idea, but seems dubious.

Here is a typical 7-pin set-up for example.
Terryallan
Explorer II
Sep 13, 2015
Fact is. the trailer lights will work with out a battery on board. You need your 7 pin checked.
mfoster711
Explorer II
Sep 13, 2015
Old-Biscuit wrote:
Trailer battery was sucking up everything that little charge line thru 7 pin could supply........5 minutes later battery had a minimal surface charge that lights could work.
That's what I was thinking.

I should have added, the battery is only 2 months old and I have a disconnect switch on it.
Old-Biscuit
Explorer III
Sep 13, 2015
Trailer battery was sucking up everything that little charge line thru 7 pin could supply........5 minutes later battery had a minimal surface charge that lights could work.
MEXICOWANDERER
Explorer
Sep 13, 2015
You need to have somone electricly savvy check out your system. Too many conflicting symptoms for this to be a single-point issue.
sch911
Explorer
Sep 13, 2015
In the future to avoid this disconnect the battery when you put the unit in storage....

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