I got a mtx 250d amp running one sub. When i shut off the car, the amp stays on and is noticeably warm. Ive tried removing the remote wire and the amp will stay on, when i remove the power wire it finally shuts off. Ive made sure the wires from the power aren't touching the metal for the remote hook up (since they are right next together).
I was trying to find an answer on google and read something about having a bad ground possibly but i cant think of why it would keep the amp on if ya had a bad ground?
Ah, good ol' MTX 250D. I used to have one a few years back. Very good amplifier I must say.
As far as the REM (remote) wire goes, you must have it installed on a constant power source which is making it constantly stay powered. I would recommend either installing the REM wire on the "Switched" Power wire on the back of your Deck, or simply hardwire it into your fuse box in the Radio Fuse. This way, every time your Deck turns off, the amplifier turns off.
If for some reason none of that is an option, your can always install the REM wire on a Constant Power source, and install and on/off switch on the REM wire so you can turn it off when ever you see fit.
Are you sure you are looking at the REM wire? If so, then there has to be an issue with the Power cable coming off the battery. I would suggest taking a look at the inline fuse and make sure it is not melting or damaged in some way.