Battery Grounded to Frame - TJ Acting Up Now

[VAWrangler]

2002 TJ 4.0 w/ Automatic

Hi all! New to the forum. Just looking for some opinions before I start spending $$$. Sorry if this is long, but just trying to give the whole story. Here is my situation... While driving the TJ my battery hold down came loose. The batter slid to the side and the positive terminal grounded to the frame. Jeep shut off completely and rolled to the side of the road. At the time, I did not realize what had happened. So I sat on the side of the road waiting for a tow with the batter still grounded. It had zero power in this state. Four ways wouldn't work. Nothing. After about 30 minutes I started poking around and saw the issue with the battery. I moved it the batter back and fixed the hold down. Tried to start it, but nothing. When the tow arrived the driver threw a jump starter on it and it worked. Fired right up and drove it home. I put my battery tender on it to get it charged up and check for faults. No issues and charged fine. Jeep sat for a week before I drove it again. Started up fine and was running fine for about 20 minutes. Then the engine just cut out. Did not lose electrical power, but it stalled. After sitting for a few minutes I was able to get it to start again. Drove maybe a half mile and stalled again. Same thing, sat for a few minutes and was able to get it started and made it home. That is where it stands as of now.

I have read a lot of things and my best guess is I messed up the PCM and need to replace it. I can find my way around working on vehicles, but electrical is definitely my weak spot. Any other thoughts or advice would be greatly appreciated. Thanks!!!

 

[hear]

One of these days I'm going to figure out what it would take to just turn the battery the other way, so that in the event it does slide, the neg contacts the tub and it's no problem.

I have mine as tight as I can get it and it still ends up with the pos touching the rubber insulator on the upper lip of the fender. That they included that rubber insulator tells me they knew this might be a problem. And I'm sure a rubber insulator is cheaper than whatever engineering effort would go into flipping the battery....but it doesn't mean WE can't tackle that problem.

You know, or just solve whatever it is that allows the battery to still move. But after 5 years of fighting it, it feels like it's time to focus on a problem I can actually solve.

 

[OldBuzzard]

Try resetting your PCM one more time. Disconnect a battery terminal, let it sit a while, and connect it back up.

Sometimes when the battery is deeply discharged, a slow charge gets it up to where the PCM starts to wake up, but since the voltage is very slowly rising, the reset isn't very clean and "flickers" in and out of reset. That can cause a variety of weird computer problems. A clean, sharp reset by attaching the cable to a charged-up battery will give it a clean power-up. It might not help, but I've seen it fix problems somewhat like you're describing.

If you need a PCM, or need yours tested, the ONLY person/company to trust is Mark at @Wranglerfix.

 

[Lou]

One of these days I'm going to figure out what it would take to just turn the battery the other way, so that in the event it does slide, the neg contacts the tub and it's no problem.

I have mine as tight as I can get it and it still ends up with the pos touching the rubber insulator on the upper lip of the fender. That they included that rubber insulator tells me they knew this might be a problem. And I'm sure a rubber insulator is cheaper than whatever engineering effort would go into flipping the battery....but it doesn't mean WE can't tackle that problem.

You know, or just solve whatever it is that allows the battery to still move. But after 5 years of fighting it, it feels like it's time to focus on a problem I can actually solve.

All you need to do is re run some of the cables and shorten some others. Pretty simple to do.

 

[hear]

All you need to do is re run some of the cables and shorten some others. Pretty simple to do.

I think I get stuck on the "special" connector that goes from the (+) to the PDC.

 

[Gilaguy23]

My 99 had the battery flipped around to prevent this. It had a top post battery with the posts toward the firewall and new/better cables.

 

[cpwolf]

I switched mine, because the only AGM replacement Advance Auto under warranty was switched. I took it as an opportunity and it wasn’t that tough a switch, other than replacing the main ground wire.

For the OP, I would say don’t just disconnect, disconnect pos and neg and touch the cables to drain, is what I’ve read

Then, if there are issues, contact Mark at Wranglerfix and he’ll ask some questions

 

[VAWrangler]

Try resetting your PCM one more time. Disconnect a battery terminal, let it sit a while, and connect it back up.

Sometimes when the battery is deeply discharged, a slow charge gets it up to where the PCM starts to wake up, but since the voltage is very slowly rising, the reset isn't very clean and "flickers" in and out of reset. That can cause a variety of weird computer problems. A clean, sharp reset by attaching the cable to a charged-up battery will give it a clean power-up. It might not help, but I've seen it fix problems somewhat like you're describing.

If you need a PCM, or need yours tested, the ONLY person/company to trust is Mark at @Wranglerfix.

I appreciate the advice. Gave it a shot and still no luck. Little more of an update on what it is doing. I was able to start it and let it sit idling for half an hour with no problem. Drove it around my subdivision for another half hour (under 25 mph) with no problem either. Once I took it out on the main road and started driving closer to 50 mph it was acting up. The shifting felt all wrong. Upshift seemed a little slow. Downshifting was very slow. Revs going towards 3000 before the downshift would come. Turned back into the neighborhood and as soon as my speed went back down the engine cut out. Still had all my electrical power. Also noticed the check engine light had come on. Sat for a minute and was able to restart and the check engine cleared. I don't have a code reader so don't know what it was. That process repeated two more times in the next half mile before I made it back to my driveway. Sounds like my next call is to Wranglerfix.

 

[hear]

Man, that feels like a crank sensor to me. It’s how my bad CPS acted, would die, but then restart w/o issue.

The shifts on your transmission are not electronically controlled, so those are unrelated.

 

[B1Toad]

I've thought about installing a big ANL fuse on the negative.

 

[macleanflood]

Was watching Fab Rats Jeepster build and they've got a nice billet looking optima mount on the firewall. Current PCM location gets in the way.

My battery also flew around during my accident...also not happy with the OEM mount.

-Mac

 

[hear]

a big ANL

 

[Feralkid]

I've thought about installing a big ANL fuse on the negative.

Why?

 

[B1Toad]

Why?

If the battery positive shorts to the body the fuse will melt. It will be just like removing the negative from your battery, no current can flow. No time delay on the ANL, it will melt instantly.

 

[g.hayduke]

You need to see what codes it's throwing.

 

[B1Toad]

Can't the generic scanners that the parts stores use read most or all of the TJ codes?

 

[hear]

Can't the generic scanners that the parts stores use read most or all of the TJ codes?

Probably, but I can't fathom owning a TJ and not having my own reader.

 

[VAWrangler]

Thought I would follow up on all this. First, I sent the PCM to Mark at WranglerFix. He was super knowledgeable and helpful just like everyone on here said he would be. We did some troubleshooting over the phone and that was when I learned if you rotate the key from off to the on position three times in quick succession the check engine codes will flash on the odometer. Turns out I did have the P0320 code. I pulled the PCM and sent it to Mark for testing. He had it tested within a business day of getting it. The PCM looked good so he sent it back. Next I followed the advice of some others on here and did the crank position sensor. Got that installed today and drove for about an hour with no issue. Fingers crossed that did it.

Thanks so much to everyone on here! Hopefully I can contribute in the future.