Red Alternator wire to starter fried! Help!

Manfreds78bay

Hi everyone, 78 FI 2.0l

After installing a rebuilt napa alternator, trying to solve my charging issue (battery not changing), my red wire that goes to the starter melted off.

I ran it for about 10 minutes, checked that she was charging, read about 13.5 volts, shut her off and smoke started coming out of my vents. I looked at the starter and discovered the red wired completely melted off. Do I have an over charging issue now? I bought a new regulator just in case.

Side note I also have a no start issue. She has to be started with a remote start with the key in the on position. Could this have anything to do with my alternator issue?

The plan is to fix my no start issue first. Then tackle the alternator.
_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

Tcash · Posted: Sat Jul 19, 2014 7:56 am Post subject:

I wish I replaced the altenator wiring harness too! HELP!!!

This is probably missing to.
http://www.thesamba.com/vw/forum/album_page.php?pic_id=1042791

Manfreds78bay · Posted: Sat Jul 19, 2014 8:09 am Post subject:

Wildthings · Samba Member Joined: March 13, 2005 Posts: 50338

As the linked thread shows the cover on the back of the alternator can ground out to the diode plate. Parts have changed over the years and Bosch apparently can't be bothered with checking that what they sell is interchangeable with the original. Having the too long studs ground out is very common, maybe close to 100%, while the link shows a deeper design to the diode plate which obviously grounds out easily as well. Someone recently posted a pic of their alternator where the PO had cut big holes in the cover to get clearance, really sad to have to do that.

We need a class action suit against Bosch on this issue. My bus died on my daughter in the middle of the night on a lonely country road without cell service because of it and it has probably caused a few fires, wrecks, and maybe blown up batteries on top of the burned out harnesses.

Manfreds78bay · Posted: Sat Jul 19, 2014 8:37 am Post subject:

I did have issues with that stud being too long and had to cut it down with a hacksaw to fit the rear cover. I put some electrical tape around the stud to prevent grounding but maybe it still arched. I'll check it out and report back.
_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

Manfreds78bay · Posted: Sat Jul 19, 2014 10:05 am Post subject:

Removed the alternator. Wiring harness is fried. So as I mentioned before, i had to cut down the B+ post to get the cover to fit. This is how it was hooked up when it failed.

Image may have been reduced in size. Click image to view fullscreen.

This is how the connection looked out of the box. There was a nut below and above the connection.

The new alternator is on the left. Not sure if you can see it but there is some sort of tape under the B+ post on the old alternator. Is this some kind of insulation from the back plate? Should the wire have contacted with the back of the alternator?

_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

SGKent · Posted: Sat Jul 19, 2014 10:20 am Post subject:

is that smoke residue from inside the alternator? If so you might go after whomever sold you the alternator to pay to repair the damage. That smoke is likely from an internal short. Battery power went down the positive wire to the starter stud then down the red wire to the alternator which appears to have gone up in smoke internally.

Manfreds78bay · Posted: Sat Jul 19, 2014 10:23 am Post subject:

On closer inspection looks like there insulation on both B+ B+ and the B+ posts. I'm guessing this insulation should have been transferred.
_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

Manfreds78bay · Posted: Sat Jul 19, 2014 10:25 am Post subject:

Manfreds78bay · Posted: Sat Jul 19, 2014 10:48 am Post subject:

Doing some testing on the D+, D-, and DF connections with the following readings.

DF to casing 5 ohms
D- to casing 0 ohms
D+ to casing 0 ohms.
_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

Tcash · Posted: Sat Jul 19, 2014 10:57 am Post subject:

Look for shorting here.

Good Luck

Wildthings · Samba Member Joined: March 13, 2005 Posts: 50338

I don't know what the resistances are supposed to be, but I would think that D+ should read the same as DF or likely higher. I would certainly think it should not be zero.

D- is a ground so should show zero ohms.

Manfreds78bay · Posted: Sat Jul 19, 2014 11:19 am Post subject:

Look for shorting here.

Good Luck[/quote]

0 Ohms from B+ to casing.

Thanks for the pic. I did find one bump on a different core I had.
_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

SGKent · Posted: Sat Jul 19, 2014 11:24 am Post subject:

I would not worry about resistance in the new alternator. The smoke residue says it is junk and should go back. Keep your old measurements if you want to really know and then compare them to the new one when you get it. Whatever shorted was enough to cook a very large wire so you can bet the alternator is cooked inside. Smoke residue confirms that.

Manfreds78bay · Posted: Sat Jul 19, 2014 11:26 am Post subject:

Tcash · Posted: Sat Jul 19, 2014 11:42 am Post subject:

Am I missing something here?

Manfreds78bay · Posted: Sat Jul 19, 2014 11:45 am Post subject:

Tcash · Posted: Sat Jul 19, 2014 12:43 pm Post subject:

I know, I posted the picture. This is what you are looking for.
Good Luck

Manfreds78bay · Posted: Thu Aug 07, 2014 7:06 am Post subject:

Success!

I rebuilt the charging wire harness. Very simple. I still had some left over connectors from my FI wire harness rebuild.

After some major delays from Napa, which I won't get into here, I finally got another rebuilt alternator. So after the feed back I received here (Thanks Tcash), I cut down the mounting studs with my dremmel flush with the nut, like the last alternator. If you look at the small hole on the boot on the red, charging wire, I believe that the long stud made contact with the backing plate and caused the failure. That hole wasn't there before.

Also if you look closer in the pictures, there were some insulators(?) between the bottom of the nut and the alternator that I did not transfer over before. The one under the charging wire is a small metal washer with a tang on it. The other is a flat piece of graphite plastic is my best guess.

I finally got to take her out last night after resolving a starting issue. I have a neat little gizmo that plugs into a 12v outlet and shows you what exactly your charging system is doing in real time. Never got over 14v. Checked the wires when I got home and everything was as it is supposed to be.

Lesson learned: Look closer at any rebuilt part before just slapping it in the bus.

_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

Slammed77bus · Posted: Thu May 21, 2015 6:14 pm Post subject: B+ b+ tested as a ground

I recently had the same problem somewhat . But as I touch the red wire to the positive on the batter it begins to spark. I used my test light to check and when I clip the alligator clip to the positive and then touched the b+ b+ bolt and the light turned on. That means it's grounded right?

Before anyone says anything the Previous owners have the batter wires backwards. The RED is negative and BLACK is positive


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Red Alternator wire to starter fried! Help!
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