I have a wheelchair motor that has a plug with 4 wires: 2 black, 1 red, 1 blue. The resistance between the 2 black wires is 60 ohms for both the motors I have, and the resistance between the red and blue wires are 4.5 ohm, 30 ohm, for each motor. The resistance between either the black wires and either red/blue was > 200 ohms. The instruction manual says something about the two black wires being for braking. Any ideas?