So I bought a 1984 Z28 and everything was working fine. Now I am facing the issue, that my battery wont charge. Already got a new alt and a new battery. Still not charging. Checked all grounds, all fuses and all relais that could cause any problems. Everything seems fine to me. But my alt still wont charge. Even when I read the Voltage on my alt it just shows battery voltage. I tried researching for a fix, but I did not find anything helpful for me. Maybe someone knows about my problem and can help me

 

There are a couple of things to check. Check the ground of the alternator case (OHMs measured between alternator and engine). Check the charging signal circuit for voltage, a “charge” light should be on if the alternator is not charging the battery, if this circuit is broken the charging field will not be excited. Try these and get back to us.

 

Does the "Choke" light come on when you turn the key on but before you start the car?

If not, first thing you should do is change that light bulb.

 

Try bypassing the exciter wire by running a wire from the exciter post to the positive terminal. I had the same problem and runs 13.5 volts on the gauge and hasnt died since.

 

I would recommend against hard-wiring the exciter wire like that.

Reason being, if FOR ANY REASON AT ANY TIME the main power output connection from the alt goes bad (loose connection somewhere, high resistance, etc.), the alt will try to power the whole system through that wire instead, which will more or less instantaneously burn up the diode trio.

Yes it has happened to me... on an older car where I did the ext reg -> 10SI conversion, and hooked it up like that because I was lazy ATM. Lasted for probably 9 months or so. Was driving down the road one day and <poof> along with the familiar aroma of the magic smoke departing from a semiconductor device.

It may work for awhile, for a REAL long time maybe even, but it's a time bomb. Sooner or later, it WILL destroy the alt.

What about that bulb? That's the problem an AMAZING amount of the time that this behavior occurs. Probably 80 - 90%, maybe more.

 

https://www.thirdgen.org/forums/elec...nals-drop.html