power probes work but you can make your own all you need is 1 a nine volt battery 2 a couple of clips 3 a roll of 5 amp wire 4 a pizo buzzer hook one end to the wire you want to trace and go looking for the other end when you find it should buzzzz
I use a multi-meter with a selection of different probe tips. I use the Ohms meter mostly since it will tell you if the resistance is too high or not. High resistance in a 6-volts system is not good.