keithholden027

1990 Toyota Pickup, 3.0l v6 sr5
Changed the alternator about 2 months ago, and about a month ago, my battery and brake light started coming on intermittently. After having the parts store check both my battery and my alternator 4 times, 3 in the vehicle, one out of the vehicle, they say there is nothing wrong with the alternator or battery.
I have tested the battery and alternator myself, and everything seems to be fine. Also checked all fuses, none are blown.
2 real problems I have seen thus far.

1-There is a .7 volt drop between the alternator and the charge fuse. Not all that important, but the more important problem in my opinion is:

2-When it is cold, all is normal. It is only when it warms up, both lights flicker on and off for about 10 minutes as I'm driving, then they stay on and won't turn off.
Again, its ONLY when its warm.

I've hit a dead stop on what to do, besides replacing more parts. I want to try and find other avenues so that I can avoid replacing parts I don't need to replace.
Thanks for all your help in advance

wyoming9

iTrader: (1)

When was the last time the Alternator belt was replaced ??

It is quite possible as it gets warm it gets loose .

Have the ground cables ever been upgraded ??

Has your alternator been checked under load once it gets hot?/

Either a heat related alternator issue

Heat related connection issue

If the belt is not the problem.

Do you have a Multimeter have you checked things when the lights come on ??

If not time to get one.

I sometimes see these tests being done I am not impressed .

keithholden027

The belt was changed about 6 months ago.

Ground connections have never been upgraded, will look into that tonight.

Alternator has always been checked under load, when it is warm.

My brother-in-law, a mechanic at a dealership, checked the battery, alternator and fuses with his multimeter a few days ago, and i checked the battery and fuses myself with one i have at home yesterday.
When he checked the charge fuse, it was a ~.7 volt drop between the alternator and charge fuse, but when i checked it, i had no voltage from the fuse, even though i had voltage at the connections for it. i swapped in 2 different fuses, same result, no voltage.

wyoming9

iTrader: (1)

When the light is on(engine running) what are you reading at the battery?

Is this just a charge light problem or alternator output problem??

Is the charge fuse loose in the fuse block.

fuse block side of connection for the charge fuse may be corroded that is not visible to your eye.

I have had the plug at the back of the alternator being corroded cause this as well.