Alternator

[reallylongnickname]

I have a different alternator. It is much bigger than your usual alternator. I doubt that its a generatorLikely it generates more current. There is pos & neg terminals of course, and also two field terminals. One is near the pos and the other is near the neg. How should these field post be set up? Should the field near the pos connect with pos terminal? and the field the neg connect to the neg terminal.

[MountainMoparRobin]

I have a 120 amp alternator which parts store's think its an generator, do you think yours is the same?

[reallylongnickname]

that doesn`t help me out. do u have 2 terminal posts for the field?

[reallylongnickname]

Didn`t seem that hard of a question to put out there. I can get the truck started but the hook up is not right on the alternator.

[wideblock]

mine has the positive term on back, no neg term, but has a case ground, and 2 fields. one field goes to ground, the other field goes to the voltage reg., unless you want to upgrade to a dual field regulator, but thats a different can of worms. hope this helps a bit.

[Jeffc]

Hard to tell what you have, seen some odd looking ones over the years, most likely it is not stock to your truck. I have seen some large ones on military rigs
but the ground post seems a little odd to me, are you sure that it is a ground?? never seen one myself on a alt....all the ones I have seen are grounded though the case to the hanger brackets and to the engine....
mmmm, may be for a second output for a duel battery system of some kind and not a ground at all? that would explain the size......and the 2 field wires unless it used the EI type regulator....

[reallylongnickname]

right now i have the pos on the alt connect to the nearest field, then it makes its way to the pos on the battery. Its first stop i think is the voltage regulator. I have the neg on the alt, grounded. there is one brown wire on the field nearst the neg on the alt going to the voltage regulator. The field on the volt regulator I assume. It starts but doesnt shut off. If connect the neg to the nearest field, the wires fry.

[Jeffc]

Is there anyway you can get me a photo of the back of your alt and regulator, it would help a lot.

in the meantime here are questions I need to ask....

1)does your voltage reg have a plug on the front with 2 posts in a tri-angle, or does it have a plug on one side and screw on wire on the other?

2)How many posts are "nuted on" on your alt and how many plug-in spots?

3)The post you assume is a ground, is it marked as such on the alt. case?

I have tied to sort this out from your posts, but it is still not clear to me, so give me a hand here.

Color code for stock alt wiring-

Black or red for battery> nutted onto the back of alt.
and heavy gauge wire

Green> field wire from volt reg (stock old system
used till 1970 in points type regulator).

Green and Brown>(2 wires) both field wires used with
the late type Electronic Voltage Reg will have a tri-angle plug for regulator.

Black> used at regulator to feed power to one side of regulator from the key switch, light gauge wire.
a)will plug into the points type regulator.
b)will be spliced into the later elct reg brown wire.

Let's see were that takes us......
IF you want, email me the photos, if you also want
click "QUOTE" in this box and write your responce
under each part, then post.....
There is also a stock drawing of
simple wiring for alt at my web page in the tech section near the bottem of page.

[reallylongnickname]

Ya I wish I had a digital cam. Maybe I`ll borrow one.
there are only 2 posts ever used on the voltage regulator. The alt has 4 nuted posts. 3 plug in spots.

[Jeffc]

Ok, that gets somewere.
I am going to guess that your truck had more that one system that ran off the alt at one time, like maybe a refer unit, construction lights or something that used a lot of power and
need anouther compleat wiring system to run it.
It may have had to have a independent ground, but you did not tell me that the post is marked a such, so I will assume that is how it came wired to you (if this is 'not' the case, then remove the ground wire).

Get a good charge on the battery. Truck will need to be running when you do the tests below. You should get a multi meter, a cheap one will work just fine for this.

How I would approch this is: Un-hook all wires from the alt.(engine off)......with truck running
taking the field wire and pulg it into one of the
field plugs on the alt., test each nutted post till you find one that puts out around 13 +/- volts. If the frist field wire post does not produce, try the next one till you find a nutted post that will works.
If you get more than one nutted post that is making the above voltage choose one and only one to hook your battery cable to.

With everthing hooked up (only the one field wire), test at battery, should get
about what the alt is putting out, may be a small voltage drop.

If you do not get the voltage passing to battery with everything hooked up:
Check your wiring from the nutted post on alt. to fire wall, under dash to alt dash gauge and other side out to battery, alt to fire wall will be black, at it changes color, fire wall to gauge will be red, guage to fire wall to battery also red to starter relay (these red wires should be nutted to the back of alt guage in dash (make sure you follow the right wire)).

You should also check to see if the voltage reg is getting power from the key switch, with key on should have 12 + volts on the plug-in side.

Electical is one thing at a time, find what works and what does not and go the next step.

If you what you can always change to a more stock type alt., you may also have to change the regulator if you do.
Do you happen to know what your truck was used for in the past?
This some guess work on my part, so can't say for sure what will happen, so
drop me a line and tell what happens.

[reallylongnickname]

I`ve got pics of alternator & motor, how do I updload them to this web site?