How come when I turn my car on the subwoofers play and some

How come when I turn my car on the subwoofers play and some times they don't? And if I turn it up it turns off
If I turn it up past 15 or the subs will turn off. as well, when I turn the car on they will not play then after some minutes they'll turn on. I checked all the wires and plugs that runs to the amp and everything is hooked up right and the power light is lit.

this is simple your negative lead from the amp must NOT go to the battery but also must be as SHORT AS POSSIBLE and have a good earth in the boot.and also check for shorts

Could be weak ground, or too small a wire to the amps, or speakers. Hard to say although.

you sub is most likely too low of an ohm blockage for you amp, causing the amp to go into protection mode,,

Mine did the same thing.turned out that the connectors on my in line fuse on my power cable going to the amp had gotten loose. I has been puzzled too because the power light was on at the amp, but then I remembered that the remote wire going to the amp has enough power to turn that on.

i agree with edward. say you have a two ohm stable amp, and you have them hooked up in parallel, that is a one ohm load. that amp wont be able to manage it, so when you turn it up, it shuts off. so i'd propose checking the way you have the subs wired and to fix therefore

make sure all your parts are able to with hold each other..