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Jeep Liberty 07 short circuit

My gf was driving our 07 Liberty today, about to park outside the house when the engine quit, and the interior filled with smoke. By the time I got out there the smoke source was no longer obvious but definitely an electrical smoke smell around the dash, and everything was dead (as if battery was d/c). I popped the hood and gave the terminals a nudge and the negative showered sparks everywhere. Decided it was an electrical short and would be dangerous to leave connected over night so, over about 5 minutes tried loosen negative terminal, battling the showers of sparks. It ended up with a sort of sustained arc, the terminal started glowing red and melting the battery housing around it and i started to panic and basically just bashed the terminal off with a wrench.

So… obviously the short isn’t routed through a fuse box. I was wondering given the symptoms above where I would start looking for a short, my guess is it has to be pretty heavy duty wiring given the abuse it took and still didn’t open. In case it sounds like something obvious to someone I thought I’d post here before I investigate further tomorrow morning.
Following fixing that short… What other problems am I likely to find? The window wipers were half way up the wind shield when I got out there and she’s (almost) sure she didn’t have them on, which has me a little worried!

Any help much appreciate anyway,
Josh

A short of that magnitude must be in or near the starter. Leave that battery cable off and check the starter and the area around your starter. The next area would be in the alternator or general area around it. Just keep looking…you will find it.

There’s not many wires other than the starter lead and alternator lead that would handle that kind of current for so long right…? I’ll have a look around tomorrow once the sun gets up. Will be buried by a foot of snow :|.

Will the battery be toast after that episode? It’s only a few months old, shame.

Thanks for your reply I’ll let you know how I get on.

I agree with the starter, but Dodge-Chrysler-Jeep products have also had more than a few electrical fires that were blamed on the ignition switch. How, I’m not sure how, since it should be fuse protected, but smoke under the dash doesn’t sound like a problem at the starter or alternator. I’ve seen fires due to a dead short at the starter, and the smoke was under the hood. BTW, if you do manage to find and fix the short, I would not trust the battery. Especially after all the arcing and hitting.

@BustedKnuckles … I agree with your assessment. The problem could be anywhere but I just wanted to point out the first places to start looking. I would not trust the battery either.

It ended up with a sort of sustained arc, the terminal started glowing red and melting the battery housing around it and i started to panic and basically just bashed the terminal off with a wrench.

The battery is toast.

Possibly door window switch:

I found the starter lead right behind the starter motor - insulation melted and core pretty much welded to the the block. Removed the lead and tested the positive lead for continuity and it was open so reconnected the battery and the dash lights up as per normal. Just trying to fish that starter lead out now, what a nightmare. Any easy way to go about that without ripping the rest of the wiring out? Any chance of pulling it through the protective tubing without removing it all…?

Thanks for all the help, will keep updating with how it goes

Am I best to try and “extract” the lead from the harness then rethread a new lead, or remove the entire harness, dismantle it, and rebuild it with the new lead then reinstall?

I clipped a jumper lead to the starter terminal and bat positive, and it fired up fine, seems to be running ok, steady ~14v or whatever it is. I’ll replace the battery anyway I just wanted to check there were no other problems before I ripped that wiring out.

I tested the starter solenoid too out of interest, ran the multimeter from it to bat positive and it clicked normally then blew my 20A multimeter, found that interesting. I would have guessed a relay would only draw a couple of amps max?

Anyway, glad to know it’s just the lead. Still doesn’t look like an easy job to replace

“I found the starter lead right behind the starter motor - insulation melted and core pretty much welded to the the block.”

So, the starter lead insulation wore through and touched the block? Any idea how the smoke got into the cabin?

I would try to extract it and run a new one. Is there enough room in the tube to run the new one without removing the ole one?

There’s what I’ve pulled out, no way it was going to come out of the loom the lead is too stiff, doesn’t pull round corners. I figured i’ll take it to an auto sparky tomorrow and see if they can re-wrap the whole thing with a new lead, and crimp some new ends. That job goes a bit beyond the scope of my gfs pink tool set I’ve been using haha. No way I was going to thread a new one either it disappears under the manifold, very frustrating to even get at. The block ground is tucked behind the oil filter it’s like they looked for the hardest place on the block to access and whacked a grounding stud right on it.

And there’s the burnt lead. I’m not sure about the smell in the cabin but I asked her about it again and she said she didn’t see the source either, could just smell it. So I guess it just made it’s way through the air vents. It has completely melted about a foot of insulation so it would have been a pretty rich smell outside.

Cabin smell most likely came through the fresh air intake for the air conditioner. Make sure if the harness has any retainers the hold it away from the block you replace them.

Thanks for the pics. They really tell the story.

Sometimes a generic battery cable can be placed over the harness assembly and the ends cut from the original cable.

However in your case the cable has melted and damaged other wires in the harness. I also see wires cut off. Rather than trying to rebuild this harness it may be more practical to replace it. The part number is on that white label, search that number and you should find a match from online dealers along with a price.

If it were me I would just see about ordering a replacement harness from the dealer, if you can still get it at least. A good shop could build you a new one at some unknown cost.

I would be very suspicious of the main battery connection to the starter solenoid if you didn’t see how the short occurred. With some solenoid connections if the stud bolt gets over torqued the head of the bolt can twist and contact case ground on the inside of the solenoid. On the outside things look okay but the stud post is connected to ground. You saw results that can happen if that is the case.

If that were the case - I would have seen shorting when I jumped the starter terminal? I was very careful I clipped the jumper lead to the starter terminal then tested for continuity to earth and it was open. Then clicked the key a few times to energise the coil and it sounded ok, then connected it all up and it fired up no problems, no smells. My guess would be the brittle loom cracked and fell away then a poor case of wire routing resulted in the starter wire rubbing through - the starter motor has had work done on it in the past few months so maybe it was carelessly put back.
Odd that the solenoid blew my multimeter though? Maybe the coil terminal is partially shorting? I should have checked for continuity to ground on that before starting, i’ll check tomorrow.

Good idea to look at the tag - I missed that one lol… I will probably go for a new one if they have it, but I need to get it back on the road ASAP I can’t really afford to wait for an order.

I have cut some of the wires, a piece out of the battery end of the red lead (short red lead) - it was melted too and I was minimising short risks but it needed to be replaced anyway, it joins the into main positive terminal mount with the other lead. And the negative lead at the bottom right was cut because I couldn’t remove the nut that secured it to the chassis. Beyond the pink toolset scope. It was under a second nut on the grounding stud, I’ll just have a new terminal mount re crimped and it can go under the first nut with the rest of the grounds (still heavy duty). And obviously the other negative terminal mount (broken) is where I bashed it off the battery when it was glowing.

So once the loom is opened up and the cooked lead is replaced, providing none of the other wires are damaged too (which would be easy to replace the light ones). I just need 4 terminal mounts re crimped and the lot to be re wrapped…

I’d say the smell came through the vents I talked to my gf about it again she said she couldn’t see the source either. There’s a good few inches of insulation melted so it would have been a pretty rich smell!

If the mounting stud for main battery cable was connected to ground internally and you provided power directly to the starter motor you would not catch the problem unless the solenoid itself was activated. Otherwise, that side of the solenoid would be isolated from the starter motor. It sounds like you have determined that the solenoid is okay. Looking at the picture of the burned wire it seems the short occurred very close to the end of the wire since it is so badly damaged. I wouldn’t mess with that old harness. You might try getting a used one from a salvage yard.