You could just multiplex both ends of the wires and then just cycle through each checking if they are connected. And for each wire on one end you could check ever wire on the other so that you could be sure that nothing got accidentally connected. Then you could use leds to display in binary which wires were faulty. Or get a cheap lcd and have it display which wires are crossed with which. A pic with about 18 pins might do it, or I am sure there is another way which might be a lot easier but I prefer to overkill instead with a microcontroller.