The image on the left shows the wires properly connected - note how the colors of the wires on both sides of the connector line up.
The image on the right shows the connection reversed.
If the colors of the wires do not line up, disconnect the wires, flip one connector around so the wires match, and firmly reconnect the wires.
(Reference 2)
Treadmill 22 shown. Your treadmill may vary slightly.
Remove the right base shroud to access the 5-pin connector.
(Reference 3)