Meters are OK for determining if voltage is present. One strand of wire will give you a reading and yet not be enough to supply the power the motor needs. Sometimes you need to use an amp meter to see just how much current the motor is pulling/needing and if the wiring is not sufficient to supply that power the motor will not work. That is one of the reasons I use an addl tail to check for power at the motor and also can jump addl power to that tail to confirm if there could be a supply problem.