If NONE of the Slides operate, then in the LF compartment in front of the LF tire is a LCI slide control module. THAT module is the control for supplying 12 volt power to the slides(regardless if a LCI or HWH Hydraulic slide). It is parking brake and Ignition key activated. Ignition Key ON and the parking brake set to operate. Tiffin also has a recall for certain models of the 2015 that adds an additional relay to help KILL that module to prevent accidental operation. IF your unit was one of those, you would have received a recall letter already from Tiffin. If this happens again, verify that the Parking Brake red dash indicator is indeed ON. If it is not, then the slides will not operate as well as the HWH leveling jacks. Doug