Well i scrambled upon this site and i am in serious need of help.Well ihave a 91 toyota truck with v6 and i was driving it and everything was fine then all of a sudden after i stopped for a while i got back in it and started it and it was fine until i take off and the volt gauge goes up to 18 and the battery light and brake light comes on at idle it does not do it all the time just some at idle but in motion it does.I took it to autozone and they said the alternator was good i pulled off the ground and cleaned it and i touched the tool to ground post and side of truck and it arked is this not normal.They are telling me alt is good but why is it saying over charging on my gauges and the lights come on?

Now i am not to mechanical inclined but i get by and this is my only vehicle right now,So please help

Thanks Kenny

 

Anyone knows?

 

Sorry i cannot help haha, id send you on a wild goose chase with my electrical knowledge all i can say is that most of the smart guys arnt on right now haha, i dont know about your time there but they are mostly online during the morning for me

 

When the brake and alternator light come on together, it's a charging problem. When my truck had the same symptoms, I changed the alternator and the problem was solved.

 

my gauge goes to 18, but it seems to be normal

 

To me it sounds like the voltage regulater is going out or already gone. It is what limits the power of the alternator... so yes your alternator may still be functional, but its dangerously overcharging... I think its the Voltage Regulator. I had a similar problem on a 1982 Toyota pickup, but on that car the voltage regulator was external and NOT part of the alternator... by 1991 I think the voltage regulator is incorporated in the alternator... check but if so you may be able to unbolt the voltage regulator from the alternator... or just replace the alternator as a whole.

my $.02

anyone confirm or deny my findings??