HELLO: KENWOOD MARINE STEREO WHEN TURNING UP THE VOLUME ABOUT HALF WAY THE RADIO CUTTS OUT TILL YOU TURN IT BACK DOWN THEN IT COMES BACK ON.

My electronics savvy source says you may be overdriving the amplifier in your Kenwood stereo to an impedance-mismatched set of speakers, meaning that the speakers are impedance mis-matched to the Kenwood stereo, and therefore operate ok (but inefficiently) at low volume, but cut off completely at higher volume.
Fix: match the impedance of your speaker network to the specs on your Kenwood car stereo. Once this is done, you should be able to crank up the volume to the point of permanent hearing loss.
SAFETY CAUTION - sound levels above 85 decibels produce NIHL (noise-induced hearing loss).
http://www.dangerousdecibels.org/education/information-center/faq/

This is an indicator of an output load problem, turn unit off! remove the speaker wires from the back of the stereo, now turn power on and turn the volume down. If the word protect stays off there is a short in the wire or one of the speakers, but! if the word protect comes on " with the speakers and wires dis-connected " it indicates a short in the audio output ic pack in the stereo.

Sounds like the head unit is bad on your audio system. You would need to replace the entire unit. I'd recommend an aftermarket stereo instead of another Ford stereo.

does it keep cutting in and out?
if so i think you have your polarities crossed
make sure you have negative to negative positive to positive

You may have a short in a speaker. Check to see that the wire terminals on the speaker itself aren't touching any metal. Even 1 terminal touching metal will cause issues. Hope this helps.

Larry T
Winona Lake, IN
http://www.cybersoundsaudio.com/cybersounds/vehiclepics.html

Have you checked all of the connections on the speakers, stereo, etc. Being a marine CD player, the wires and connectors are exposed to more elements than a car CD unit. Check for corrosion and make sure that all the speakers are hooked up to the correct "+" and "-" terminals. Not sure if this will help, but thought I'd try. It does sound like a speaker connection problem.

Did you try turning off the source for the other zone. Goodluck.

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.