Issues with voltage at starter post?

[Zachary]

Hey guys,

So chris and I were just about to get my car all started up for the first time, I popped the positive wire on its battery terminal yanked it off because we saw a giant plume of smoke coming from the engine bay. When the smoke cleared we saw that a green wire that runs from the post on the started solenoid to the post on the alternator had cooked. Everything else was fine. We dug around in one of the parts cars and found a replacement wire, checked all of our grounds, called mark allision, looked at brad artigues wiring guide, and once we had replaced the wire and connected a couple brown wire contacts that were not hooked up before. We tried it again.

No smoke, no burning, but also no power getting to anything.

The battery reads 12.3 volts on the multimeter, and so does the large green positive wire that connects to the starter, but as soon as that wire is on the starter, it drops down to 0.32 volts. We cant figure it out. Does anyone have any ideas?

I will study the artigue wiring guide again tonight.

[divace73]

you may have a dead short......

[spider2081]

The wire that connects the alternator to the starter is a something like a #8 wire and can carry a lot of current. For it to burn I would think there was a short in the alternator. If the short was in the starter no current would have flowed through the wire connecting the alternator to the starter. I would disconnect the wire from the alternator and see what you have.

thoughts. Are you sure the battery was never connected reverse polarity?
Is the battery fully charged now
are you sure the large terminals at the starter are not shorting to anything

[narfire]

Hi guys. Yea a bit of a puzzle. 12.3 V at the battery. 12.3 at the large green wire from the battery to the starter solinoid but not attatched to the solinoid. Connect to the solinoid and voltage is as Zach says.. .32V. Is there a chance there is a dead short in the solinoid? We connected the brown wire to the solinoid,wire from solinoid to alternator and no power when the ignition engaged Meter reads .32 at alt post and solinoid post and 12.2 at the battery. Looked at my 80 tonight and same wires/connections. Car turned over a month ago before the aux shaft/fuel pump issues.
Chris

[azruss]

If you have a direct short in the starter, you would get a huge arc when you touched the battery cable to the solenoid post. enough of an arc to burn a big hole in the post. same would be true on the battery end. sounds like your battery is bad. reads 12V with no load, but drops to nothing with a load. Before frying a new battery, i would have the alternator tested to make sure you didnt fry the diode. Also, a direct short in the alternator should produce fireworks as well.

[So Cal Mark]

sounds like a voltage drop, have you checked both power and ground circuits for voltage drops?

[dhagood]

mark, how does one do that exactly?

[spider2081]

An example of measuring for a voltage drop would be to put one lead of the volt meter on the battery post and the other on the battery lead right at the post. If the connection is good the meter would read 0. If there is resistance in the connection the meter will read a voltage. That voltage is a drop and not available for the rest of the circuits. Every connection is capable of a voltage drop. Another way is to measure the voltage to ground at both parts of a connection. Again at the battery measure the voltage on the post and then on the cable terminal. Subtract the readings and the difference is the voltage drop.

One common problem in trouble shooting is to have a mind set there is only one problem causing a symptom.

This issue started with the wire between the starter and alternator melting. Replacing the wire is not a likely fix for why the wire burned in the first place. It does fix the wire. This wire is large so it can handle the charging current for the battery. Also on that terminal of the alternator is a smaller wire that feeds other circuits in car. If that wire didn't melt then something was shorting at or near the output post of the alternator for the large wire to melt.
That is why I would disconnect the wires from the output post of the alternator before reconnecting the battery. Remember the large alternator wire is hot as soon as the battery is connected so you should tape it terminal.
Be sure the battery is charged before trying to connect it.
I think this will help find why you have the voltage drop at the starter terminal.
Let us know how you make out

[Zachary]

So today Chris and I changed the battery after doing a volt drop test on the other one, I replaced the old battery ground wire and cleaned up the area where it grounds to. after doing all of that we checked if the starter would turn if it wasnt connected to the alternator. The starter began to turn, so we tried to hook the wires back up to the alternator and got bad arcing with the post. We got fed up and put in a new alternator, hoping that the issue was with the diode, but after hooking everything back up again we got arcing when trying to reattach the positive terminal to the battery.

I put together a brand new ground wire for the battery, but we are still pretty stumped as to what is going on. The issue has something to do with the alternator causing a short I think. I really dont know.

[kmead]

Sounds like an issue with the alternator or the wiring as you have it installed.

How is the ground wire from the engine to the body? If it had to transfer all of that energy it too could have been cooked.

Karl

[spider2081]

I don't have the wire diagram for a 79. Is there more than one wire on the output terminal of your alternator?? If there is I would take them all off. Then starting with the big wire that goes to the starter reconnect them one at a time to the alternator and recheck with the battery connected. If the big wire by itself causes the spark I think there is a chance the new alternator is bad. If there is a smaller wire that also connects to the alternator output and it causes the spark it could be a number of things. In a 1980 wire diagram this wire feeds fused circuits for the horns and cooling fan. Also it feeds the cigar lighter and the parking lights. All of these bypass the ignition switch and are hot all the time. If the parking lights happen to be on or the cigar lighter is pushed in you would get a good size spark. However this would not indicate a problem.

I would also take the first alternator to and have it tested. Most chain parts places like Pep Boys will do this at no cost.

Don't give up be for the "miracle of success" happens

[thefiatek]

1)Disconnect the battery.
2)Unhook the wire from the alternator (the one with the green sheathing) it should be black.
3)unhook this same wire from the starter (it should tie in with the brown wire)
4)unhook the brown wire from the ignition switch and OHM it to ground <100 OHM = wire shorted
5)inspect junction block. You should find a short to ground through the junction block ( 3 Browns).

If Not:
1) Connect the wire to the alternator
2) OHM the brown wire from the ignition switch ground. <100 OHMS = Alternator shorted to ground.


If Not:
1) Unhook alternator wire, connect brown wire to starter
2)OHM brown wire from ignition switch to ground <100 OHMS = starter shorted to ground

If Not:
1) Unhook Black wire from fuse #10
2) OHM from black wire #10 to ground (alternator wire disconnected)

If none of the above locate the problem OHM the completely disconnected battery cable to ground. Somewhere you will find a dead short. I've got my bets on the brown wire.

I

[narfire]

Thanks very much guys. I'll print this off and take it to the shop tomorow and if Zach makes it in..he has some checking to do.
He looked a tad dispondent this afternoon. With this advice ,he'll be up and sorted in no time. The other thing I'm goint to check is to make sure the alt. post is insulated properly. I'll take a close look at my 80 and see if Zach's has the same insulating material around it. Could be going straight to ground I'd guess when I try to attatch the wire from the starter solinoid to the alt post and big sparks happen. If this is the case,would the diode be hooped?
Chris

[majicwrench]

I so hope you have polarity correct at the battery. The alt diodes will flow currrent if battery not connected right, producing big short when hooked up. Good luck

Keith

[narfire]

I so hope you have polarity correct at the battery. The alt diodes will flow currrent if battery not connected right, producing big short when hooked up. Good luck

Yeup,got that part right. Put the battery from my car in as well. I think the fiatek is onto something with the brown wire. I remember when contacting the alt. post from the starter post the alt post was grounded...big spark. The brown wire was connected onto the alt post at that time. I looked today and there is a grounding strap,but the ground was a tad muddy so I did'nt get a good look at the connections,regardless, I'll make up another grounding strap and in the meantime just use a jumper cable frame to engine to be sure. I have a friend(fellow that builds by fiat heads) comming over tomorow to have a look see and poke about a bit.
Chris