power problems,alternator, electrical, or something else?

i just changed my alternator for the second time last week, a week later once again my charge battery light and brake light came on again but the difference now is that when i check my battery with a volt meter the readings are correct, i even got my alternator and battery tested seperately at autozone and they both passed, some times i can drive for hours without the warning lights coming on but on some days the lights will come on and turn off when i accelerate about 2000rpm but when i slow down or hit the brakes the warning lights come back on.Any suggestions of what could be causing my brake light and battery light come on?

While you are checking voltages wiggle the wire harness between the battery and alternator and the main battery cables. Battery cables especially can corrode internally and give you fits. Clean all the power connections. You are getting at least 13.5 vdc at idle across the battery terminals correct? Are you checking voltages when the alt and brake lights are on? What year and engine?

i agree on cables..it may be your pos. cable going to starter..but like he sais they can corrode inside..good luck...

I would also check the alternator belt for proper tension. Did you install a new belt along with the alternator? If so, new belts have a tendency to stretch and loosen up after a bit of driving; especially aftermarket belts.

Mike

i tightend the belt properly and the lights still came on. As far as checking the votage when the warning lights are on, sometimes it will read 13+ volts and sometimes it will read 12. i can ride for a while without the warning lights coming on, example i drove the car today and the lights didnt come on, i start the car up again about nine hours later and it is fine, thirty minutes after that i start up the car, rev the engine and the warning lights come back on and dont turn off like they would before at about 2000rpm, but when i rev the engine to abour 4000rpm+ they cut off and turn right back on when i brought it back down to idle.