Welcome to 2CarPros. Nice ride.
Before you do anything, test it using two jumper wires and power directly from the battery. If you apply battery voltage with the wires one direction, and the motor goes up or down, then reverse the polarity and the motor goes the opposite direction, the motor is okay. If it still only turns one direction with the polarity reversal, the motor is bad.
If it does reverse okay then you have a problem in one of the switches. Grab a digital volt meter and connect it in place of the motor. When the switch is moved one way read the voltage and pay attention to the symbol that may show up on the meter saying - or neg. Most meters will indicate if the leads are connected "correctly" by showing a - sign if they are reversed. That symbol will tell you if moving the switch the other way is reversing the polarity or not. So say the first time you move the switch you get a reading of - 12.3 Now move the switch the opposite way. You should see 12.3 if the polarity is reversing.
If you see the same reading both times you have either a wiring or switch problem.
Friday, June 19th, 2020 AT 1:42 PM