I have a 1987 Ford ranger xlt and I switched from the stock stereo to a aftermarket and when I did it turned on played you could hear everything but when you turn the truck off the memory just wipes out. So after 5 months I bought another head unit thinking the head unit was the problem but after I switched them out it still did it to me after rechecking the wires to make sure it was correct and the only wire not hooked up yet is the remote wire for my two 10 in mtx's. Can someone help cuz having to keep setting everything is a pain in my you know what

 

there should be a battery constant wire (green/yellow) and accessory switched (yellow/black) and it sounds like both might be switched in your case because you are losing all power to the radio. check to see if you have power on the green/yellow with the ignition off.