Motor can only push the sliding doorslightly open. Motor closes the door most of the way but quits when it tries to pull the door shut at the end. Since this problem only happens in extremely cold weather, can I eliminate the wiring harness and focus on the rear latch maybe being stiff or in need of lubrication? When the motor mechanism is disconnected, the door travels easily so door lubrication is not the problem either. Any help is appreciated.