Amp runs but then will just turn off and red light comes on

have you checked the fuse and also the relay.

Also could be that the power wire and earth wires going to amp are to thin amp could be heating up and could be going into protection mode. Will switch on after it cools down what gauge wiring are you using?

the amp probably got to hot and had a thermal shut down witch will have to be fixed by a professional.

check ground cable, check fuse on amp, and check the fuse under the hood, on the positive cable should be about 12' from the battery, if all is well and theres no light, check the blue wire coming from your deck use a tester,if bad you can run one of your fuse box ,place a 12volt switch and hook it to the amp you should be good to go

you may have fried the amp pre outs in the head deck, try the amps on another stereo

sounds to me like you are overheating the amp, try down tuning the peak level of the amp, and also if there is anything around the amp clear it away, check if the fan is turning on, you may need to replace it,

Sounds like the amp is going into Protection Mode. Does yours have green LED light then RED LED on it? The green is power and the red is Protection. You will need to either change the OHMS wiring or Put A Fan on it to Keep it Cool Inside.

disconnect audio inputs and outputs and see if one of those are causing it , if it still does it with all audio inputs and outputs disconnected then there is a problem with the power amp

Are you sure that the terminal isn't shorted to the case of the amp?

If it's not, the amp probably has a shorted output transistor.

If you want to repair it yourself, read through the following page. It explains the basics. Let me know if you have any questions.

Basic car amp repair primer

This is not a ovehaul light. It is called the protect indicator. It kicks in when the amp detects a fault on it's output. Disconnect the speaker / sub. Power up the amp and see if the light goes out. If it does you Sub is toast and needs to be replaced. If it stays on then the amp is done.