Well here we go again...brake/charge lights come on, lights go dim, blower motor slows down etc. you get the picture. Checked and double checked belt tension, all connections, and bench tested alt. Funny thing is: when i start the truck cold it charges normally until it warms up a bit. Also, the brake/charge lights will go off when shes runnin above 2500-ish rpm, and eventually will charge after extended periods of high rpm. Can anyone shed some light here? Thanks.

Replace the brushes and go from there

http://www.4x4wire.com/toyota/maintenance/alternator_brushes/

Been there, done that. I actually replaced the original alt with a NAPA because i needed one fast and they had one, and the original alt was trashed anyway. Only thing left to do is take the NAPA back, which i dont wonna do again because pulling that bottom rad hose and then refilling is not fun <img src="/forums/images/graemlins/drunk.gif" alt="" />

well i have had a simalar problem with my 90 toy p/u look around the driver side of the engine compartment look for a larg plug with 3 or 4 wires make shure they arent burned up if they look ok check the main power cable it should run near the larg plug and have a break in it a small plastic box where the wires lead into it its held together with a bolt see if those are coroded or burnt hope that helps you a lil bit

This makes me think bad diodes. After it gets warm it can't handle the current any more and goes to a higher resistance or quits till it can cool down. At higher RPMs you still get charging due to the other diodes passing enough current.

I dunno if this is related, but when my alternator gave me problems it ended up being one of the screws holding in the brush pack was stripped. It happend to be the one with the ground strap attached too, so it was making intermitent contact. if you've already done the brush pack though that doesn't make much sense. I'd be inclined to agree with Bogo as well, especially since bad diodes seem to have a tendency not to show up in bench tests. Also, you *can* get the alternator out without taking off the radiator hose, but it usually hurts. If you take out the lower radiator bolts you can usually wiggle it free and not mess with coolant.

My guess is a bad solder joint inside the alternator. Connects when cold & opens when warm. You're probably gonna have to pull that alternator one way or the other...