Amp problem

[BahnE30]

rents bought me a 500w amp for x-mas so i had an amp in it previously, took it out and sold it. needed the cash. so anyway it works perfectly until you start the car, then it goes into protection mode until you shut the car off, but as soon as you start it back up it goes back into protection mode again.
any ideas and yes all the grounds are good

[StereoInstaller1]

Check your alternator voltage, you might be overvoltage.
Luke

[BahnE30]

and fix this how

[jht3]

get out your multimeter (you DO have one i assume) and test the voltages while off, ign, and on. and recheck your grounds

report back

[BahnE30]

i have a volt meter just have to find it in the heaping pile of tools

[BahnE30]

threw the volt meter on it, and the car is charging at 13.8volts car running so thats not the problem

[jht3]

threw the volt meter on it, and the car is charging at 13.8volts car running so thats not the problem

wait, did you test the voltage at the + terminal on your amp?

[BahnE30]

yeah, figured testing at the battery wouldn't mean a whole lot