Help...electrical short

[Hasdrubal]

Officially stuck..at least I'm at home. Decided to open a new thread for this problem, hopefully I can get some ideas from you guys. Had to replace the fuel lift pump yesterday, at the same time I swapped in a new filter assembly. went to bleed the system today with an air compressor @5psi. Got no joy so decided to do it the standard way by cranking. Pulled the pink wire from the IP, went to turn her over.

Instead of cranking I got an unusual other sound and noticed a puff of smoke from my rear battery negative post. Didn't have it turned on for more than a second. A small part of the battery post has melted. I have done no electrical work except for the connections to the new filter assembly. I believe it shorted as I went to start and not when it was power on. The truck has run withought problems before this.

After triple checking everything I could think of before the sun went down and it drops to -8. I found the following; 1) On the red cable that goes to the starter near the lift pump where it drops over the frame rail edge, it appears a small groove has worn into the jacket where it has been rubbing. Couldn't tell if it was deep enough to get to the core. but I wrapped it in electrical tape. 2) On the negative bus bar, the innermost terminal was slightly loose, tightened it. Everything else looks good.

Am I correct in assuming this short was starter circuit associated? I haven't tried to crank it again out of sheer apprehension. I can only hope it was the starter cable rubbing on the frame rail. Is there any way I can test this withought cranking?

 

[nk14zp]

Sounds like a loose terminal.

 

[Hasdrubal]

All battery terminals clean and tight with dielectric grease. Bus bar connections tight. New batteries.

 

[Hasdrubal]

Woke up hoping someone here would have posted some incredibly usefull insight or some past experience leads. Major disapointment, here I've had all sorts of suggestions thrown at me; bad starter, starter solenoid, battery, starter relay. Have had a starter go bad and a battery die, neither of which produced rear battery neg post welding syndrome. Going back out now with a friend to brainstorm over the beast.

 

[Westech]

I know what your problem is.... I can figure any thing out by just the owner telling me what he/she thinks happened and I never have to look at the truck/car.... I have been ASE for over 16 years and I know it all just by a post....

Its Broke.

Come on hippie you really think someone can give you the Magic fix over the net? Its up to you to figure it out. We can only give you thoughts of what MIGHT be causing the issue. If you cant do it alone take it some place and have a professional work on it.

Love Westy

 

[Hasdrubal]

Yeah well, getting someone else to fix it, particuraly electrical has never really worked out for me. Have a couple of CUCV guys up here. the best consensus is; a smoking battery terminal sounds like a dead short in the starter wiring. Of course it was more than smoking it was welding and melting the battery terminal. If it ws a bad sterter, solenoid, or relay..would it produce this?

 

[mistaken1]

A car battery puts out 400-500-600 amperes of current at 12V. Two in series means the same amperage at double the voltage which means twice the power of a single battery and until they discharge those batteries are a welder.

I believe that red wire leading to the starter always has 24V on it. If that wire shorted against the frame there would be a lot of current moving from the negative post on the front battery to the positive post on the back battery. That wire would burn itself clear or weld itself to the frame which I assume would cause the batteries to explode.

When large amounts of current flow any high resistance connections get hot. So if your back battery negative post melted that tells me that it got hot, meaning there was high resistance there.

Since the current only flowed when you tried to start the truck then I suspect something bad in that starting circuit. I could be a bad starter or perhaps your back battery is bad.

You won't know until you start testing each component. I would start with charging and load testing the batteries.

 

[Hasdrubal]

Started snowing so its curtailed my troubleshooting for now. Getting another battery later to swap out the rear one with before I try to crank it up again. Front battery showed 12.69V, rear 12.8V.

Checked all the cables in the start circuit, connection on the starter is tight and clean. No heat shield there, the cable end has braces on the side to prevent it from turning when tightening. No signs of chaffed or charred cables.

 

[dependable]

I would check the battery cable down by the starter, there is a heat shield there that frayed though ever so slightly one one of my trucks a while back. It usually started, but the arcing fried a solenoid that was new. Someone told me there were sparks under the truck when I started it one night, clewed me in.

 

[doghead]

You were just working(bleeding the fuel filter) near the rear battery post. Did you lean on it? You may have simply had a loose terminal, and that would cause the terminal post or cable to melt when you cranked it.

You may have a starter motor brush lead shorted(worn out brush).

 

[Hasdrubal]

Yes, I was leaning over the passenger side on the terminals and had not desconnected them. I believe it was tight as the rest of them. That being said I would be overjoyed beyond belief if it was only a loose terminal clamp. Will find out tomorrow when I test it with another spare battery.