PRODUCT DESCRIPTION
The Combination Slide-out Controller with Voice functions as three controllers. It independently controls two lock
arm motors and a slide-out motor. The controller depends on several inputs: Lock Arm 1 Switch, Lock Arm 2
Switch, Slide-out Switch, MPX Switch, and an Ignition Input Signal, which is used to lock out control module.
THE MPX SWITCH
The MPX Switch is a momentary rocker switch used to allow the user to select a run/stop mode of the Controller.
The MPX switch is connected to the Controller through connector J3 pins 8 (MPX IN) and 7 (MPX GROUND)
Installation Manual
Awesome source for hard to find parts. 
