My Kenwood Marine Stereo KMR-350U shuts off after it has run in the USB mode for a period of time.

Depends on how much sun is beating down on it and the amount of water it has been exposed to. Warm is ok, hot isn't.

open and clean your car stereo receiver and check it again

Do not wire it directly 2 a hot wire...Wire through the ignition

Kenwood TDF42D Detachable Faceplate may be purchased here:


http://www.partstore.com/Part/Kenwood/Kenwood/KDC225MR/Kenwood/Kenwood/TDF42D/New.aspx

you need to use the blue/white wire instead of the solid blue to turn the amp on. solid blue is antenna remote and shuts off when leaving tuner mode. blue/white is amp remote turn on.

could be thermo electronic component normally mounted on the inside of the unit...its to protect against over heating

It's probably a voltage regulator that feeds the main power amp. It will need to be replaced if it is. The way to find out would be to spray the faulty device with Servisol Freezer spray while the system is up and running. If it then goes dead it would confirm it's faulty.

It sounds like there is a short somewhere in your wiring. If the problem got worse when you installed the aftermarket stereo then it may be on the factory side of the plug. You may try powering the stereo by some other means. For example, try a wire with an inline fuse directly from the fuse block to the power wire on the stereo. You can also tap into the ignition wire that way the only way it will get power is when the key is turned on. Don't forget the inline fuse if you try it that way. I had to do that with a stereo I once had.

I had this same exact problem when my last older Kenwood Marine stereo cooked itself while I had it up loud for a few weekends on the lake. (smelled like it had burned inside). I went out and bought a new Kenwood KMR-550u stereo deck. (I do not have an additional amp). I hooked it up to the exact connections where my older Kenwood stereo unit had been hooked up, as I never had a problem with this for the past three years until it failed after smelling of burning elelectrical. I had chalked the problem up to heavy rain we had one day. Every time I turned up the volume, sometimes up to 27 out of 35 possible, or 29, or 32, the stereo would suddenly shut off as if I had turned it off. After a few seconds the stereo would come back on, but unless I was quick enough to turn down the volume it would do it again right away. Of course on a boat, we were beached in a cove and the engine was not running when I encountered this. I searched the internet finding hundreds of similar complaints and several dozen theories of all types, but only a couple that pointed me towards the power (voltage) idea as the problem. I put a volt meter on the positive & negative wires powering the stereo. I watched as I gradually turned up the volume, the voltage on the power wire gradually decreased from 12.5 volts, down into the 11 range, and as it hit 10.9 or 10.8 volts it shut off typically around a volume of 32. The red power wire in my boat that never seemed to have an issue with my old stereo until it fried was determined to actually be inadequate for the power flow for the new Kenwood, and probably was the culprit of my failed older unit. I offer this sound advice: Run a new pair of positive & negative wires directly from the battery (with an appropriate fuse of course (the deck has a 10 amp fuse in it's back so I would use that at the battery) to the stereo. Check the voltage as you turn the volume up into the high 20's and low 30's to ensure you are still getting voltage in the mid to high 11-12 volt range. The stereo is designed to require a minimum of 10.8 volts to operate, and when it drops below that it protects itself and shuts down.