Alternator problem

[Stan Gundry]

I posted this on the SDC Forum and have not received much help. Maybe Someone here can.

Several weeks ago I completed the conversion from the original Prestolite Alternator with external Voltage Regulator to the bolt-in 1988 Toyota Tercel Alternator with internal Voltage Regulator. I followed the instructions for the conversion carefully and even had my local old-timer mechanic confirm that I was wiring it right.

Every thing seemed fine from the get-go. It charged the battery for 3 or 4 minutes after starting and then the needle on the Ammeter settled right in the middle the dial. I have driven it 4 or 5 times and probably put at least 60 miles on the new set up.

It was fine, until today. When I started it up today to take my great grandson for a ride (yes, he appreciates the finer things of life like I do), the Ammeter showed a significant discharge, both with the ignition key on and with the car running, a discharge of about 10 amps if the Ammeter is to be believed. gunning the engine made no difference.

What is the likely problem? A bad Alternator/internal Voltage Regulator (purchased a rebuild from Rock Auto)? A short in my original wiring harness (I did take the precaution of installing a 60 amp fuse in the cable that goes from the Bat. terminal on the Alernator to the + terminal on the Ignition Switch)? Something else?

What tests can I do to find out what the problem is? Right now I am thinking I should have stuck with the old Prestolite, but the new setup seemed to promise more reliability.

[IndyJimW]

With the engine running at about 1200 rpm read voltage between battery terminals, should be 13.1 volts or higher. If not, alternator is probably not working. I only use new alternators when possible because of the poor quality of todays rebuilds. I looked your alternator up and saw that none of my suppliers offered a new one.

Check the fuse, if it blew that would cause the problem that you are having. I checked Motor Alldata and the alternator you have could have a output of up to 70 Amps.

Edited July 9, 2012 by IndyJimW