Positive battery terminal contacted body, Jeep wont start

Stoney938

Stoney938

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So I was driving my 2.5L 5 Speed manual 99 TJ Sahara down the road and every now and then it would act like it lost a surge of power, I wasn't sure what was happening until i took a hard left turn and it just completely died. Luckily I was in my drive way but I had 0 power and resetting the ignition position did nothing.
So I checked under the hood and saw the the battery had slid under the lip of the fender inside the engine bay. I disconnected the both Battery cables from the posts for a minute, put them back on and I had power again. I hopped back in to start the jeep and as soon as i turned the key all the power cut back out.
I was having the same exact issue a few months ago when I first picked up the jeep, but that was being caused by a bad battery. So I obviously thought it had been fried / damaged like the last battery so I took it to Auto-Zone to get tested, but this time it tested good and fully charged. I brought it back through it back in the Jeep, got power, turned the key and it all crapped out as soon as i turned the key.
Any ideas? I'm thinking best case scenario i fried the Starter Relay or something similar. Starter and Alternator are brand new. Thanks
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I'll have to look but there's likely a fusible link in the harness that may need replacing. Give me a minute to look in the manual, and I'll explain...

Nevermind. I re-read your post title, and it wouldn't be a fusible link problem because the B+ terminal touching the frame bypasses the fusible link. I did look it up, and instead of fusible links, it uses maxifuses (edit: No, it doesn't - keep reading) in the PDC.
 
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Classic battery cable problem. Check both ends of both battery cables for corrosion, tightness. Disconnect them, clean them.

With corrosion on a connection, low currents can pass for lights and such, but as soon as you hit it with a big current for the starter, it becomes a high resistance and acts like a dead battery.
 
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Yeah, I'm familiar with all the fuse types, but I've only opened my PDC up one time, over two years ago, and I couldn't recall what's in there, so I was using the manual, but we all know how accurate that is. :rolleyes: My post with the manual page above was purely about learning if the manual is wrong, not necessarily defending my answer.

I found this photo in a thread jjvw posted many years ago about an auxiliary PDC he wired up using an XJ PDC:

1715806942784.png


The TJ PDC is on the left, and the XJ PDC is on the right. It looks like they copied and pasted from the XJ FSM into the TJ FSM - the XJ has MAXI fuses, but the TJ has JCASE fuses.
 
sab said:
Yeah, I'm familiar with all the fuse types, but I've only opened my PDC up one time, over two years ago, and I couldn't recall what's in there, so I was using the manual, but we all know how accurate that is. :rolleyes: My post with the manual page above was purely about learning if the manual is wrong, not necessarily defending my answer.

I found this photo in a thread jjvw posted many years ago about an auxiliary PDC he wired up using an XJ PDC:

View attachment 527137

The TJ PDC is on the left, and the XJ PDC is on the right. It looks like they copied and pasted from the XJ FSM into the TJ FSM - the XJ has MAXI fuses, but the TJ has JCASE fuses.
Click to expand...

My XJ box is completely reconfigured using the guts of multiple Chrysler PDCs. The internals are modular blocks that get stacked up inside the enclosure. I couldn't tell you what those maxi fuses or relays came out of.
 
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jjvw said:
I couldn't tell you what those maxi fuses or relays came out of.
Click to expand...

Here are some MAXIs in a 96 XJ PDC in this NAXJA post, showing the same 2x7 MAXI bus as in your auxiliary PDC:
1715812002651.png


1996 was the model year immediately before the first TJ, so my copy-paste accusation stands. :ROFLMAO:

Not that it matters, especially for the OP. I'll just slowly back out of this room... :sneaky:
 
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I guess I'd just start with a multimeter and see if you have power down at the starter and you get 12v on the smaller cable when you turn the key.

You're lucky you didn't start a fire.

Probably melted something someplace. Smell anything?

IMG20230719131932.jpg


-Mac
 
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macleanflood said:
I guess I'd just start with a multimeter and see if you have power down at the starter and you get 12v on the smaller cable when you turn the key.

You're lucky you didn't start a fire.

Probably melted something someplace. Smell anything?

View attachment 527176

-Mac
Click to expand...

Mac, quit showing off your winch durability test results!
 
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sab said:
Mac, quit showing off your winch durability test results!
Click to expand...

That wasn't the winch...that was the fuse I put between the pdc and the alternator.

Note to self...tighten your bolts on the lugs...then check them again.

I actually haven't melted any winch power cables yet... just the motors.


-Mac
 
macleanflood said:
I guess I'd just start with a multimeter and see if you have power down at the starter and you get 12v on the smaller cable when you turn the key.

You're lucky you didn't start a fire.

Probably melted something someplace. Smell anything?

View attachment 527176

-Mac
Click to expand...

i didn't smell anything, and with a quick glance didn't notice any damage to the battery cables. once this rain lets up i'll get out there to check the fuses and battery cables.

That's pretty damn gnarly
 
Read through the thread and didn’t see it mentioned….i know it isn’t the topic at hand but did you make sure to secure the battery down so it doesn’t make it under the fender lip again? Your battery should not ever be able to move. You are indeed lucky a fire wasn’t started from this.
 
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machoheadgames said:
Read through the thread and didn’t see it mentioned….i know it isn’t the topic at hand but did you make sure to secure the battery down so it doesn’t make it under the fender lip again? Your battery should not ever be able to move. You are indeed lucky a fire wasn’t started from this.
Click to expand...

Yup, that is the plan once i get it running again
 
so a few years ago i looked into the "Big 5" or "Big 7" upgrade i think its called? Pretty much replacing all the major battery wires with a bigger gauge. Worth looking into?
 
sab said:
Here are some MAXIs in a 96 XJ PDC in this NAXJA post, showing the same 2x7 MAXI bus as in your auxiliary PDC:
View attachment 527169

1996 was the model year immediately before the first TJ, so my copy-paste accusation stands. :ROFLMAO:

Not that it matters, especially for the OP. I'll just slowly back out of this room... :sneaky:
Click to expand...

this is what my PDC looks like in my TJ
 
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Stoney938 said:
so a few years ago i looked into the "Big 5" or "Big 7" upgrade i think its called? Pretty much replacing all the major battery wires with a bigger gauge. Worth looking into?
Click to expand...

I've heard of the big 3 in audio context, IIRC it's battery pos, battery neg, and alternator charge wire?
 
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