Generator not charging 58 Suburban 235

[JoeSal]

Hello guys,

Just got the truck back from mechanic after engine rebuild. I do have a few things to sort out. The generator is not charging the battery. I had this problem before I took it to him. While the engine was out I had the generator rebuilt. They also tested the voltage regulator and told me both are working. I believe they are connected correctly.
Trying to read up on where the break could be is a little confusing.
If I go with the assumption that both of the things are working properly and the break is after the regulator. How should I proceed?

I am having a hard time following the red 12 ga wire that leaves the regulator (on the wiring diagram) Does it go to the ammeter?

From the ammeter, I think I can see (on the diagram ) a black wire going to the starter, a red one to the ignition switch and I think a red one going to light switch.

If the regulator does need to be checked, how do I know if it is a single or a double contact. testing seems to be very different.


Thank for any guidance.
joe

[_Ogre]

it has been a looong time since i used a generator
but i do remember having to polarize a generator that has been disconnected
it was done by shorting 2 terminals on the regulator
i googled ''polarizing a gm generator'' and came up with this from the hamb
as i remember it is the right proceedure but...
do me a favor and don't do this until someone else chips in and says yes

1.take a 4 inch piece of wire...strip the ends off to make a jumper wire
2.touch the Batt. terminal on the regulator with one end of your jumper wire
3. with the other end touch the Armature terminal on the regulator while still holding the other end of the wire on the batt terminal. (on the regulator)
4. You'll see a small spark, don't be alarmed.When it sparks remove the jumper wire.
5. You will be good to go. Just did this the other day. It's easy to do.but intimidating if you haven't done it before

[JoeSal]

Thanks Ogre,

I was just able to try polarizing this evenning. It did not work. I am trying to find the wire that charges the battery, if such a thing exists. There is one wire that goes to the starter that is not hot. Not having much luck with the wiring diagram. I think the previous owner did a lot of cut and paste using maybe earlier model wiring/switches/instruments etc. and it is very hard to follow.

The problem is that is that my skills are limited and I dont really know how the electrical system works. It is all a learning experience.

I am starting to doubt that the generator was correctly rebuilt and in working order. same for the volt regulator.

I was thinking about switching to an alternator in the future. I already have the bracket and "conversion" wire but I kind of wanted to put it back together as it was before I made the change. I didnt want to make the switch and still have problems cause of faulty wiring or another issue.
Not sure if that makes sense. The conversion may not use all of the same wires and my problem may be solved. But it is never that easy... he he.

I will read up on the conversion. and somehow figure out how to test the voltage regulator and generator without pulling from the truck.

Thanks again.
joe

[JoeSal]

duplicate

[Wrenchbender Ret]

Use a test light & make suer the red wire on the reg. is hot at all times. Take a jumper wire & hook the field wire (the smallest wire) to ground. Run the engine & see if it charges. If it does the gen is good. Don't run it very long of fast like this. If it doesn't charge you have a reg. problem or wireing.

[OrrieG]

I cannot add anymore other than to say that when you replace a generator always replace the voltage regulator too. I learned that lesson early on.

If you are new to the game find an old Chiltons manual from the 60's, they are reproduced. In the back they have component theory, diagnosis and repair sections. Over the years I have also collected old body work and automotive repair textbooks. For the most part this is not rocket science, just methodical testing and diagnosis, usually a simple problem.

Electrically it usually boils down to a bad ground or poorly connected wire. Check the connectors and routing to make sure there are no shorts to bodywork or other metal.

[JoeSal]

Wrench Bender Ret and OrrieG

I hope to have some time tomorrow to try again.

I will test the red wire on the regulator. I do believe it was hot the whole time (with a light test).

Just for my understanding.... I will connect a jumper from the field wire, on the regulator, to a grounded location.

Run the engine and check if it charges at the battery with volt meter?
(to 14?)

or am I checking at the ammeter on the instrument bezel to be right of center?

I will try to get my hands on some old Chiltons. I do have the reproduced shop manual for the truck.

Thanks again, joe

[Wrenchbender Ret]

I would ground it at the gen first in case thev wire from the reg. to the gen. is bad. You can gauge it either way. The voltage may run up over 14 though as this bypasses the regulator. That is why it is important not to run it very long like this.

[JoeSal]

And I am checking voltage at the battery right?

[Wrenchbender Ret]

You can check it at the bat or the bat term of te reg.