charley1972

My 91 4runner is having issues charging. It will start fine, just will not charge more than about 12V. I pulled the alternator and had it tested it was fine. I have changed the battery terminals, new ground straps, still not charging corectly Any ideas

scyotapu

voltage regulator could be bad. have you swapped a diff alternator into it just to make sure yours isnt bad?

charley1972

I will hook it all up to voltage meter and an amp meter to see what its doing. I kinda figured it was the regulator, but it cant be changed separate from the alt.

Hilux808

Most likely sounds like your alternator has issues but doing a few other checks doesn't hurt. Do a voltage drop test on the positive side of the alternator circuit, while the truck is idling measure the voltage from the output post on the back of the alternator and the positive battery terminal. If you get higher then 0.20 volts then something is wrong. Make sure all connections are clean.

Read this article on alternators and testing...
http://www.aa1car.com/library/charging_checks.htm