Jeep battery dead after towing

[Potcakes]

We flat tow our 2014 Jeep Wrangler and have for years. The last two times we towed, we couldn't start the Jeep without a jump. After the first time I took it to the Jeep dealer and had the battery, alternator, etc. checked and everything was fine. After the first jump, we had no problems at all until we just towed again today and now we have the same issue. The only thing that I an say is different is that one tail light is out when we tow, it is on in normal operation, just out when towing. We have changed nothing else, except to add a battery disconnect after the last time (5 days ago) We towed from FL to NC with multiple stops, no issues, then it happened and now it did it again.

We use a M & G braking system, have had it for years and it works off the airbrakes, so no power going there. So we only have the wiring harness beyond that.

Any ideas? I don't even know where to start on this one!

[mowermech]

DryCreek wrote:
Another JK owner with 2011 reporting no steering wheel lock. Pull the key, lock the transfer case in neutral and transmission in 6th. Oh, parking brake off - don't want to forget that ya' know.

When I was towing a 2006 Wrangler, I put the transfer case in Neutral AFTER I connected the towbar to the motorhome. That way, the Jeep was held firmly in place, so no need to set the parking brake. If the brake isn't set, you can't forget to release it.
Besides, IMO it was MUCH easier to move the Jeep to the motorhome than to back the motorhome to the Jeep!

[DryCreek]

Another JK owner with 2011 reporting no steering wheel lock. Pull the key, lock the transfer case in neutral and transmission in 6th. Oh, parking brake off - don't want to forget that ya' know.

[dubdub07]

Heisenberg wrote:
My 2014 Wrangler does not have steering lock. I pull the key ....

Wrangler's after 2008 (and some 2008s) do NOT have a steering wheel lock. Put it in park after the transfer case is in N and pull the key.

Problem solved.

Bill

[Tom_Barb]

IT_Burnout wrote:
"when your disconnect is on the negative, the battery can't be discharged. it is making a ground some how.


I agree, which makes you wonder if the cutoff switch has some continuity through it somehow. The Parasitic test would help to prove that out if its performed. I bet either the minute you plug in the MH the meter would show a current draw. Or if something else is wired direct to the battery and touching the battery side of the disconnected switch. That could in effect provide a ground path back through that connected devise and be working right around the disconnected switch to provide a ground. I also agree just physically disconnecting the negative side of the battery cable would probably stop the whole issue.

Read above, he said they put the switch in after it went dead the first time. the late models like the 17s are a circuit board nightmare for old mechanics like me.
I'd call "cool Tech" and have a talk.

cool tech

[IT_Burnout]

"when your disconnect is on the negative, the battery can't be discharged. it is making a ground some how.


I agree, which makes you wonder if the cutoff switch has some continuity through it somehow. The Parasitic test would help to prove that out if its performed. I bet either the minute you plug in the MH the meter would show a current draw. Or if something else is wired direct to the battery and touching the battery side of the disconnected switch. That could in effect provide a ground path back through that connected devise and be working right around the disconnected switch to provide a ground. I also agree just physically disconnecting the negative side of the battery cable would probably stop the whole issue.

[Tom_Barb]

Potcakes wrote:
I will check for a fuse, I"m not sure about that.

We have the battery disconnect to on the negative, but since it only happens when we are towing and it happened before and after the disconnect being put on, I suspect it must be in the wiring harness. I think I have the old harness from a previous MH and Jeep, so I may try to see if that will work and cause the same problem. If it does, then I think the problem must be in the motorhome part.......of course this plan only works if the old harness fits!

So, a short somewhere could cause the battery to drain in 5 or 6 hours, even if we have the battery disconnected (the negative side)? Is that correct?

when your disconnect is on the negative, the battery can't be discharged. it is making a ground some how.
you must isolate the battery post. we remove the battery cable each time and place a plastic cap over the negative post.

[enblethen]

If you are disconnecting the ground from the battery, you have a bad battery.
Have you checked your battery disconnect switch to make sure it is operating?

[Heisenberg]

My 2014 Wrangler does not have steering lock. I pull the key ....

[Sam_Spade]

IT_Burnout wrote:
Just a suggestion, I would do a parasitic amp draw test on the toad by itself then do it hooked up to the MH.

An even better suggestion:
He SAID that the battery went dead WHILE DISCONNECTED.
If that is true, ignore all of this because the battery is bad.

[IT_Burnout]

Just a suggestion, I would do a parasitic amp draw test on the toad by itself then do it hooked up to the MH.

It’s a pretty easy test to do. Buy a cheap multimeter with (auto-ranging is easiest to understand) with an amp port, you can get one from Amazon for under $25.00. Then hook your meter in series with the negative side of the battery to measure for amperage. Not in parallel with the battery to measure for voltage. Set you meter accordingly. Take a look at this youtube video and he goes through the process on what you need to do. Also take a look at this video you want to be careful with the meter leads when you are done measuring amps put you test leads back in the voltage ports so you don’t cause another problem which he explains. You can get the amp prob he suggests, or not, you just need to take some care when performing the process.

Start out with the toad unhooked everything powered down and in a condition where you know the battery doesn’t get drained. So you should see a normal current draw. Then hook up to the MH and see at point your current draw ramps up. Then start disconnecting things or pulling fuse until you zero on what is causing the draw and back track that circuit to see if you can find the issue. You might be able to get a fix on what is happening relatively inexpensively.

If nothing else once you change something (cable, ect)you won't be shooting in the dark so much. You should see some change is amp draw.

Bob

[Sam_Spade]

Potcakes wrote:

So, a short somewhere could cause the battery to drain in 5 or 6 hours, even if we have the battery disconnected (the negative side)? Is that correct?

No. Absolutely, positively NO.

[Potcakes]

I will check for a fuse, I"m not sure about that.

We have the battery disconnect to on the negative, but since it only happens when we are towing and it happened before and after the disconnect being put on, I suspect it must be in the wiring harness. I think I have the old harness from a previous MH and Jeep, so I may try to see if that will work and cause the same problem. If it does, then I think the problem must be in the motorhome part.......of course this plan only works if the old harness fits!

So, a short somewhere could cause the battery to drain in 5 or 6 hours, even if we have the battery disconnected (the negative side)? Is that correct?

[Tom_Barb]

What wiring harness do you have?

some how the battery is finding a ground, or the opposite, to complete the circuit.

We remove the ( - ) and isolate it with an old plastic cap.

[enblethen]

Does the MH have separate fuses for the trailer connector?
Yes, a loose wire in a connector could be causing fault. Normally this should blow a fuse as light outages indicate.