Wiring, need a little help

[AlexFolino]

Well i finally know whats wrong, missing the isolation parts but at this point i have to have this truck running in the next 2-3 days... Im just kinda screwed here. Partly by sitting on my you know what for over a year on it and now with the help of the great people of this site i finally know my issue but the parts i need i just cant find locally. I see you can get the stuff online but i feel at this point ill just buy a caddy alt for now and the current isolation(less) alternator will sit in my tool box for a while.

 

[mistaken1]

Double check that your current driver's side alternator is an isolated ground unit.

 

[Warthog]

I would check the drivers alternator and make sure it is still isolated (you can check it with a Ohm meter, check for reistance between the ground terminal and the case).

If it is working correctly, then install it on the passenger side, buy a caddy alternator for the driver side and then look for parts to fix your busted one.

Once you find the parts, fix it and keep it as a spare or reinstall it.

Just don't give the parts house your old one.

 

[AlexFolino]

Theres no way they are getting my old one hahah.. How many ohms should i see for it to be isolated?

 

[doghead]

Infinite, no continuity to the alternator housing.

 

[AlexFolino]

Do i need the key on engine off?

 

[doghead]

To eliminate any possible wiring issue you may or may not have, I suggest you test the alternator isolation, with nothing connected to it.

 

[AlexFolino]

Well the day has finally come. The truck runs! Called a local rebuilder here and he was able to get me the fiber washers and the bolt isolators among other misc things i needed. Went home, rebuilt it and voila! Not only are my GEN lights coming on and going off like they are supposed to, but im getting 28 volts when running!!! Truck has started and shows proper voltage key on and key off the past few days. I tested my volt gauge however and it is infact bad so ill need to buy one of those but at this point i cant stop grinning. Thanks everyone for your help!

 

[Warthog]

Every once in a while us old timers know what we are talking about.

Good job on getting it fixed.

 

[epartsman]

I agree!!!! Yes you guys do know what you are doing.

 

[wisconsinz]

e tach output nee

This may sound harsh but don't take it that way.

The pictures you attached are ones that I took and posted.

From your description, someone HAS been in the alternator and "forgot" to reinstall the "isolated ground" components. "Oh I don't need that, let me through it away"

You MUST have all the fiber washers and bolt insulators in place along with the black jumper wire.

Item #22 for the rectifier bridge needs the washer and bolt insulator

Item #18 for the rectifier bridge needs the washer and bolt insulator for the "neagtive ground post"

The tach output needs a washer and bolt insulator

The positive Terminal needs a washer and bolt insulator

The voltage regulator and brush holder need the three bolt insulator

The point of all this is to separate the internal electrical components from the outer metal case.

The jumper wire connects the rectifier to the regulator and brushes

Finally got the alts tested and I'm about to rebuild. I first rebuilt them in 2013, but it seems they're shot. Both stock alts are identical (have the isolated ground post), other than the capacitor on the passenger side being on the outside. My questions are:

1) why on the outside of only one of them?

2) Do I rebuilt them the exact same way even tho the cucv wiki says the drivers side alt is not an isolated ground? But of course connect between engine block and terminal post on the drivers side.

thanks guys

 

[wisconsinz]

Basically just trying to figure out the difference between these two alts before I rebuilt them. Thanks.

 

[MarcusOReallyus]

The capacitor on the back can be tossed. It's to suppress radio noise. Both had them in stock form. You don't need it, and it doesn't really hurt if it's there.

In stock form, the alts are identical. Both isolated ground.

However, only the 24v one MUST be isolated. The 12v gen doesn't care.

The stock alts are identical because it was much simpler to have just one alternator and not have to worry about which side it gets installed into.

 

[wisconsinz]

The capacitor on the back can be tossed. It's to suppress radio noise. Both had them in stock form. You don't need it, and it doesn't really hurt if it's there.

In stock form, the alts are identical. Both isolated ground.

However, only the 24v one MUST be isolated. The 12v gen doesn't care.

The stock alts are identical because it was much simpler to have just one alternator and not have to worry about which side it gets installed into.

Thank you kindly!