Wiring cooking itself. Going crazy.

[Olee]

Recently I replaced the alternators on my M1008. Exact same model that was originally in it. I hooked everything up according to the wiring diagrams provided by the TM's. As soon as I start the truck the fusible link (from the ground on Gen2) on the junction box above the master cylinder cooked itself. I've been over wiring and stared at the TM's until I was blue in the face and I can't figure out why it keeps doing that. Any assistance would be greatly appreciated.

 

[Warthog]

Post a pic of the backside of the alterntor you installed.

Do you have a voltmeter and know how to use it?

 

[Olee]

Unfortunately my voltmeter is on loan to a buddy who left town until after the new year, but here is the image you asked for.

 

[o1951]

That does not look like the isolated ground Alt I put in friend's truck.

 

[Vhyle]

That does not look like the isolated ground Alt I put in friend's truck.

+1. The passenger side alternator MUST be an isolated ground alternator. It doesn't look like that one is. If there is a grommet there, it's very hard to see, but your problems would make sense if that alt isn't an isolated ground unit.

 

[Olee]

The alternator does have a grommet on it and I was assured these are the correct alternators by a shop that had ordered two for another guy here in town. Called the store. It's a Wilson rebuild. Part number: 90-01-4277. Same thing mentioned by Warthog in another of his posts if I remember correctly.

 

[Warthog]

It is a isolated ground. The red wire w/white strip is connected to it.There have been new and rebuilt units that have not be built correctly. They leave out the internal isolating washers. Only way to find out is to test with a meter.EDIT. The Wilson units are known to have issues. You need a meter to test.

 

[Olee]

What do I need to do to check if the ground is actually isolated or not? I'll be the first to admit I'm no pro when it comes to electrical.

 

[MarcusOReallyus]

You need a meter. A ten dollar El Cheapo from Lowes will do in a pinch. With the batteries disconnected, check the continuity between the case of the alternator and a good ground on the vehicle.

Some voltmeters have a continuity check setting. Usually, it beeps if you have continuity. You do NOT want it to beep.

Otherwise, use the Ohms scale (resistance). There should be ZERO Ohms. No connection.

 

[Olee]

Borrowed a tester. Alternator casing is reading continuity to the engine, ground post, and everything else I can think to touch it to. Time to get my warranty to work for me. Thanks for the help so far. Will post again when I resolve this issue.

 

[Ken_86gt]

You need to disconnect the "isolated" ground wire from the terminal, and the rest of the wires to be safe, and verify that there is no continuity from the post to the case on the alternator. Testing with the wire on may not give the correct results.

 

[Olee]

Put the warranty to work and got my new alternator in just a few minutes ago. Truck is running like a champ with no wires trying to BBQ themselves. Thanks for the input everyone. Much appreciated. Sad part is y'all had it figured out after a brief description and a single picture. Maintenance crew at my unit couldn't figure it out for over 2 weeks with it right in their face.

 

[Warthog]

As soon as you said Wilson, the solution presented itself. We have seen it too many times.

Where do I send the bill????

Glad you got it fixed. The SS club has another happy customer.

 

[steelandcanvas]

Sad part is y'all had it figured out after a brief description and a single picture. Maintenance crew at my unit couldn't figure it out for over 2 weeks with it right in their face.

That's why we make the "big buck$".

 

[Skinny]

This makes me want to install a nice big maxi-fuse on each alternator and eliminate that near thirty year old fusible link system. Glad it saved your rig from catching fire or burning up a harness.

 

[doghead]

That 30 year old fusible link just worked perfectly and saved his truck, after he created a dead short.

Why would you re-engineer that?

FWIW, 15 seconds on precaution(testing the new part) would have prevented all of this. It's not like we haven't discussed this to death and it's hard to find in the forum.

 

[Skinny]

Why would you re-engineer that?QUOTE]

Easy to replace roadside. I've had a couple in another type of older vehicle fail just due to age/condition which is a bummer...especially in the rain or cold. Plus it gives me something to do

 

[MarcusOReallyus]

What he said.

I don't like fusible links. Maybe I'm in good company, since pretty much everybody has quit using them.

 

[o1951]

What he said.

I don't like fusible links. Maybe I'm in good company, since pretty much everybody has quit using them.

I am not a big fan, but reality is they are ok, and a good choice in offroad under hood environment. Factory links are well sealed, and still perform well 30 years later. I like fuses, but have to say underhood, unlikely they will last anywhere near 30 years. Contact corrosion.