My indash jensen radio keeps shutting down when turned up?
Sounds like there's a power problem. First take out the radio and leave it connected. Turn on the radio normal volume, then disconnect the radio's antenna. If the radio shuts off then you need a better ground. If the radio doesn't shut off then you need to run power wires to the fuse box.
The only other thing is you have a bad speaker that only shorts out when you turn it up. Disconnect all but one speaker or one speaker at a time and see which one is the problem.