Quick question for all of you who are much smarter than me.

I posted threads a few years back about an electrical short I was having in my Roadrunner, 383 auto with a mopar mini starter on it.

The battery was disconnected. When I connected the battery, it fried wires under my dash and my main power feed wire to the ammeter. The key was not even in the car, lights were in the "off" position.

My question: Could a bad starter short out and cause such wires to fry like that?

The car was sitting for several years before I hauled it to our new home across the country. Maybe sitting caused something? The starter is over 20 years old and has spent most of its life close to the header pipe.

Thanks in advance, Eightlitermopar

For anyone bored that wants to see the original threads, here are the 2 links:

https://board.moparts.org/ubbthread...in-walk-me-through-this.html#Post2642205

https://board.moparts.org/ubbthread...in-walk-me-through-this.html#Post2642205

I would think a direct short at the starter lug would isolate any damage to the main battery cable and none under the dash.

Hmmm, that is kinda what I was thinking too. The main hot wire that goes under the dash is attached to that wire which is why I thought I would ask. I didn't have any problems for 20 years. This happened suddenly. Now the car sits and it's driving me crazy.


I have a cheap multimeter from harbor freight, but I don't know much about finding shorted wires with it. I can't hook up the battery because the short is still present.


Electrical isn't my strong point, but I'm slowly learning. I still may pull the starter and bench test it, but It's probably a light switch or something simple like that.

Thanks!
eight

I once dropped a plug and it shorted the battery - I knew because its sounded like a gunshot when it blew the ground off the connection. That too a while to find because it was bolted to the wheel tub behind the battery box in the trunk.

agreed. you might disconnect the battery positive cable & pull one fuse at a time & with the meter on ohms touch one lead to that cable & the other to ground & see if there is no longer any continuity to ground after you pull a certain fuse. Might be a start

Just guessing but what about a shorted alternator? I know a shorted out alternator would fry the fusible link first but what if the fusible link didn't do its job? 2 years ago I had a shorted alternator and the fusible link fried when I hooked up the battery cables to the battery.

Correct me if I'm wrong but shouldn't the power feed going inside come off the starter relay not the starter itself? Pretty sure mine's a fuselink off the relay...only thing on the starter is the main batt cable and the switch wire(also coming from the relay)

I had the same thought. I actually changed the alternator and voltage regulator just in case 2 years ago when this drama started.

the bug has bitten me again and I've started messing with it again. I'll figure it out eventually.

My two guesses were a starter or a corroded light switch or something. I'll let everyone know if I find something.

eight

Could be the ammeter itself. Not unheard of.

Could that be tested with a multimeter? Its basically a free flowing channel of electricity isn't it?

Bypass it

As others have stated, you need to put your ohmmeter on the battery leads (no battery!!!) and start disconnecting things until the reading significantly increases (higher ohms is a more OPEN circuit.)

The alternator power wire— the heavy wire on the stud, is the first thing I would disconnect.

I'd pull the instrument cluster and look at the wires at the back of the Amp gauge. All the power goes through that gauge and if the nuts holding the wires on are the least bit loose, they start to arc and can produce enough heat to burn the ends off those 12 gauge wires. If that is where the problem is, it won't be hard to see the issue, anything less that a pristine connection on both wires indicates a problem. Gene

I've seen the hot leads off the alternator and starter relay/fusible link melt into the firewall connectors due to too much corrosion on the connectors. Don't overlook this part of the harness as the culprit. All the juice to feed everything but the starter main wire runs through those two leads, either from the battery to the ammeter, or the alternator to the ammeter..

I wanted to give an update for today. With lots of good advice I wanted to take the effort to update results. Not sure if I made any progress today though.

1) Replaced the starter relay. I had a spare laying around, so it went in.

2) Since I love to do things as complicated as possible, I jumped the starter directly from a fresh battery and it was VERY SLUGGISH. Did not get one single engine revolution out of it. The jumper cables were VERY warm afterwards. Pulling some amps.
I fought some headers and got the starter out of the car and bench tested it. It worked great on the bench, engaged and spun fast. Put it back in the car, same slow result. When a load is placed, it’s tired. Ordered a new starter. Maybe this was the problem? I hope it’s that simple.

I cleaned up the fat wire to the starter, made sure there were no broken or melted places.

3) I did some poking around with my ammeter on the ohms setting.

I placed the one end on the POSITIVE cable side and started checking with the other. I checked the following:
There was a reading on the “hot” alternator stud. I figured this was to be expected.

No readings on from the coil, positive or negative side.

I checked the park lights on the front since I was up there and resting in the shade of the car. No reading.
The fuse box. See picture attached.

I got a reading on all fuses on the left side and the “battery” spot on the bottom. All light related. Is this not to be expected?

If the starter doesn’t fix this issue, then the light circuits are my next focus. They are suspect.

I’ll let you know if the new starter actually works.

Thanks again. I appreciate the patience.
Eightlitermopar

the starter needs two things to work properly, a good, clean connection at the stud and a good clean connection to ground, this includes the negative battery cable. Did you do any oltage drop tests?

When a battery positive melts/burns it obviously has touched ground. The damage to the hot wire will only be as far as the ground source. If your dash wiring melted there are only 2 sources coming through the firewall. The black wire from the alternator output stud. And the blue fusible link from the starter relay. This wire is red on the inside of the car. If it didnt burn the fusible link the issue is in the black wire circuit.The black wire has splices feeding various items in the dash. The ignition switch, headlamp switch, horn relay, fuse block, and ammeter. Follow the melted black wire circuit under the dash until the wire isnt damaged. At that point you'll find your issue.
Doug

I have not done a voltage drop test. I haven’t gotten that far into the process yet. I will put the new starter in since I have it ordered. You bring up a good point about the ground, I will recheck this.



The positive cable did not melt, but it is a large welder feed wire that I made many years ago. It may have more ability to hold that kind of amperage if it did get overloaded? I took it out and inspected it, nothing looked too terrible there. The fuseable link burned all the insulation off but did not evaporate the copper. That wire all the way to the ammeter in the dash is what fried. The ammeter studs were not burned at all. I will find a picture from one of my previous posts. Like others have said, the ammeter is on my list of questionable possible culprits. I may just bypass it to see if that solves the problem once my starter is put back in.

I’m just messing with the car on my days off here and there between work and other family duties, but I will post updates as I move along.
Thanks again.
Eight.

If it fried all the way to the ampmeter. And did not fry the other wire at the ampmeter ? Then the ampmeter itself was the ground path and is your issue. Remember the damage will cease after the ground point.
Doug

I will double check, but if my memory serves me right, it was only the wire from the starter relay. It fried the fuseable link and the wire through the firewall to the one side of the ampmeter. I hope this is all it is.

eight