So here's the breakdown, 1980 toyota pickup w/ 20r engine 4wd, replaced battery to find out that alternator failed. Replaced alt, drained the battery again, recharged battery and decided to replace external voltage regulator. Still won't charge battery, replaced in line fuses and engine fuse under dash, cleaned grounds on engine block and next to battery and alternator wiring. Run battery test and voltage drops below 12 when running still! Sooo ... any thoughts or past experiences that may help me with this bug my truck has?

here's the current wire setup on the alt

no idea what this wire is, comes out of the same location as the alt wires, but wasn't hooked up on the previous alt or ever for as far as I know... leads to here

but does not go into voltage regulator wiring

these are the only inline fuses I could locate

Appreciate any help,
Aloha, Jacob

 

Are you sure the new alternator has the correct pin out?

There are multiple options for the same plug. Check this out, scroll down to NipponDenso

http://s7d9.scene7.com/is/content/Ge...any/1704040pdf

 

Not sure, but I would assume so seeing that it's an exact fit on the wires. That link said that was for the voltage regulator wiring though... correct?
question, I can only get my battery to charge up to 12.05 volts on the external charger... should the alternator still be able to push it up to 14+ volts if it works properly

 

With the engine off, your batt should be arnd 12v. Mine are usually 11.6 or something bc theyre not brqnd new.
with the engine running you should be reading 13.5 ish. However your battery is not actually holding 13v, thats just a measurement of electricity with your alternator generating into the system. But if your engine is running and your only reqding 12v, your battery is not charging and will quickly drain.
a 12v battery should be 12v ish when fully charged.

If you were getting 14v on a charger, you might make a big explosion.

There are 2 types of alternators
those with internal regulators
Those with external regulators

 

Does your charge light on the dash come on with engine running?
does it come on with key in accesory position?

You also have a charging relay

 

If im reading the diagram right, you should have a black wire going from alt to regulator