Wiring, need a little help

[mistaken1]

Is the passenger alternator an isolated ground unit? If not and you connect the 12V positive of the front battery to the ground on the passenger alternator when you go to connect the 12V negative post on the front battery it will see a dead short.

 

[AlexFolino]

Yes...i do believe its an isolated ground alt.

 

[AlexFolino]

I went out and snapped more pictures and have more questions, i have a blue wire coming off of positive board that runs to a red 8 GA wire that goes no where. It came out of the wiring harness running down passener side out of a plastic holder that says 6 on it. Could this be an issue to my melting battery terminal? Also i noticed a ground coming off the firewall that goes nowhere either. Im willing to bet it goes to a ground on the head or such. I know everyone keeps saying check the TM but im having trouble finding what i need on there and its just not getting this fixed, its freezing up here in PA and i dont have a garage so im doing this in the cold id like to just get an answer from the more experienced on here so i can just get this on the road he he. Im not the best with reading electrical and i just need as much help as i can get. i appreciate it tremendously.

 

[Terracoma]

I went out and snapped more pictures and have more questions, i have a blue wire coming off of positive board that runs to a red 8 GA wire that goes no where. It came out of the wiring harness running down passener side out of a plastic holder that says 6 on it.

I have a blue wire coming off of positive board that runs to a red 8 GA wire that goes no where. It came out of the wiring harness running down passener side out of a plastic holder that says 6 on it.

This connection (blue 12-gauge fusible link to a red 8-gauge wire) originally went to the positive lug of GEN2.

Also i noticed a ground coming off the firewall that goes nowhere either. Im willing to bet it goes to a ground on the head or such.

Your photo looks like the mystery ground is a braided strap.

The ground strap should connect the engine block (intake manifold stud) to the firewall.

I notice in the schematic it says supressor coming off the red/white wire. Do i need to add another wire off of that to ground to the frame?

Disregard this suppressor, it's absence will not affect your functionality.



.

 

[Terracoma]

Before i started rewiring the truck the pass alternator had the red/white going to the positive terminal on alternator, no wire going to the ground, the only wire that came off the alt was the red wire coming from the plug and it went to the passenger positive board.

Sounds like maybe the PO wired the alternators and batteries in parallel to make it 12V rather than in series.

Agreed with mistaken1... Alex, do we know what voltage your current starter takes?

I'd hate to see you pour your effort into returning the truck to 24v if it's already converted to 12v.

 

[mistaken1]

I did this, everything is correct.. this is why im so confused.

Scan or photograph your drawings and upload them so we can see what you are seeing.

Please do not take this as an insult or attack because it is not, it simply is an observation of fact. If everything is correct you would not be melting battery terminals. Something is wrong.

I have had plenty of experience where I believe everything is correct yet it does not work so obviously something is not correct and that is when it is time to go back to the basics and check everything step by step. Usually what happens is I find something I overlooked or I assumed was correct and passed over.

Yes...i do believe its an isolated ground alt.

Don't believe, test it and know. Did you buy and install this unit? Did you check it before installing it? There have been reports of alternators sold as isolated ground unit that were not truly isolated.

 

[AlexFolino]

Ok ill do this in a bit. What do i need to look for to make sure this is an isolated ground alternator?

What do i need to do to make sure i have a 24v starter in it as well?

 

[mistaken1]

Us an Ohm meter or continuity tester and measure for continuity between the ground stud/terminal and the alternator case. You should read open between those two points.

If it is not open and you connect the front battery positive to that stud/terminal then the entire chassis is charged with 12V positive so that when you connect the front battery negative post it will now see a dead short.


I have not personally checked but others have stated they are stamped 12V or 24V. May have to remove it to find any markings. Hopefully someone who know more about this will chime in.

 

[AlexFolino]

As im waiting for my sister to get to the house with the scanner i put the truck back to how it was when i got it for ****s and giggles. red/white to pos on back of alt. I started truck and was getting 26.7v across both batteries running. 14.3 on battery 1, 12.7 on battery 2.

With key off at red 13.01v at GEN 1
12.2v at GEN 2

With key on at brown 12.7v at GEN 1
12.7v at GEN 2.


What i am seeing is no 24v at GEN 2 readings.. Not sure if this would help at all but its just somethingi noticed.

 

[AlexFolino]

Rebuilt passenger alternator, installed 2 new relays. Now i got a GEN2 light on. Never had that in the past. GEN2 light stays on all the time though and still no rear battery charging. Im going to trace all wires on the pass alternator now because im still melting terminals. Would not having the fiber washer on the passenger red/white ground wire to alt cause this?

 

[mistaken1]

Rebuilt passenger alternator, installed 2 new relays. Now i got a GEN2 light on. Never had that in the past. GEN2 light stays on all the time though and still no rear battery charging. Im going to trace all wires on the pass alternator now because im still melting terminals. Would not having the fiber washer on the passenger red/white ground wire to alt cause this?

Yes, if not having it allows the red/white ground wire to contact the alternator frame/body.

In a stock 24V system the ground terminal of the passenger alternator is connected to the positive terminal of the front battery (not directly) so that you can read 12V from that passenger side ground terminal to the vehicle chassis.

The frame/body of the passenger alternator is bolted to the engine which means that the alternator frame/body is electrically connected to the vehicle chassis. In a correct passenger side alternator you will read 12V from the ground terminal to the alternator frame/body.

If the ground terminal of the passenger side alternator is physically contacting the alternator frame/body internally or externally (electrical continuity between the alternator frame/body and ground terminal) then you have a dead short there. If the last thing you connect is the batteries the large current flow (like a welder) takes place at that point where you finally complete the circuit (battery terminal).

If the passenger alternator is NOT an isolated ground unit (no electrical continuity between the alternator frame/boy and ground terminal) then you have a dead short and will melt battery terminals when you try to connect them.

 

[AlexFolino]

Thats the best news ive seen in years!.. cant wait to get home and try this out. Im feeling very confident now. So i need to find a fiber washer somewhere(which store), then run an 8gauge red wire to positive terminal board, red/white to this ground stud on alternator and then hope for the best.

 

[Warthog]

When you rebuilt the passenger alternator, did you follow the re assembly instructions in the TM 9-2320-289-34 manual? Did you reinstall ALL the internal washers and screw insulators?

If not the you do not have an isolated ground alternator and will see fireworks when reconnecting wires.

 

[AlexFolino]

That i did, the only thing i was missing was the outside fiber washer for the ground post.

 

[AlexFolino]

took the alternator apart just to make sure im 100% on my fiber internal washers and i was. as looking on this site however i noticed that on the inside, the capaciter goes to the rectifier which i have but i seen on some alts on this site theres another black wire that goes where the capaciter and rectifier attaches then runs along the curve of the case up to the top of im guessing a stud which mine does not have? Im going to need this i guess, is it anything special or can i just make one of these wires and put ends on it? Also where can i get these external fiber washers? Local parts stores here kind of are stumped and im wondering i could use nylon?

 

[Warthog]

Post a picture of what you have inside the alternator. Sounds like someone else has messed with it and left some things out.

You can possibly go to an Electrical Supply house and get a fiberglass flat washer, find one online or use the one in the Positve Terminal kit from CUCV Electric. I'll messure one off of a spare alternator this afternoon.

http://www.washersusa.com/stockportalf.html Catalog B30

http://www.amazon.com/s/?ie=UTF8&ke...rial&hvadid=4287962025&ref=pd_sl_6pknod0o7s_e

http://www.cucvelectric.com/posterm.html

 

[AlexFolino]

Ill have actual pictures of mine tomorrow in the am.
I have pictures of somebody elses online here and...

Pic.1. I made the wire i dont have yellow in this picture. Can i make this wire? If so what gauge is it?


Pic2. I see i dont have fiber washers under my rectifier which im going to address. Other than this though and im reading the TM wrong i believe but where i have the yellow arrows here, do fiber washers go under the screws here also?

 

[Warthog]

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

 

[AlexFolino]

I got some pics that ill post tonight, at this point i might be better off putting the driver side alt on the passenger and buying a cadillac driver alternator. Im missing atleast 2 bolt insulators and that jumper wire.

 

[badassissimo]

I've heard it's better to stay cucv on the alternator. Worth the moneys too. Hang in there Alex. I'm hoping you figure out what's wrong with yours so I'll know better about mine. I'm thinking it's my dash so I'm rewiring the whole charging circuit. If it doesn't work, I'll be back to checking this thread.

Nick