88 and new is controlled by the ecm but on 87 and older there is voltage regulator bolted to the firewall.

 

On my truck I got rid of all the firewall modules and b.s etc..so there's only or wire running the engine. The vr was new but with all the testing it could of went bad? But I know there is nothing left? I did find a conversion kit for my alt. To change it over from 3 wire to one wire for $39.00 ! It might come down to it?? Thanks guys again for your input and help!

 

so what is the voltage regulator bolted to? if it is no longer bolted to the firewall then it may no longer be grounded which is why it is not working.

 

U got me still have the vr bolted to the firewall in the stock position. I cleaned the mounting area and grounded the vr!

 

So that fixed it then?

 

No I was just saying what I have done! Going to try another vr this weekend? Thanks again

 

Good luck bud. I hope you get it figured out soon!

 

well i finally got around to trying a new vr and still no charge !! i tested the vr plug with the key on i have power at both terminals on the vr plug ! should i have power at both terminals with the key on ? or just one ? thanks

 

I had the same problem not too long ago and it ended up being the VR. I know it sounds stupid but is everything grounded properly? I had the same issue when I installed the new alt. I had stripped off all the wires around the battery and when I re-hooked everything one of my grounds was hanging, causing the system to ground out. The Alt was charging but the Volt gauge dropped like a stone.

 

You should only have power at the top terminal with the key on. If you have voltage at both, something is wrong and that will cause it to pop the new reg as soon as you turn the key on.