The LiftMaster 71-909210MD Field Mod, Dual Aux Limit Switch is a genuine LiftMaster add-on kit that provides two auxiliary limit switch outputs for select LiftMaster commercial door operators. By adding separate contacts that change state at the fully open and fully closed positions, this dual auxiliary limit switch kit enables reliable door status signaling and integration with external devices such as traffic lights, horns/strobes, interlocks, dock equipment, access control panels, and building management systems. It’s a practical replacement part or upgrade for sectional and rolling door operators used in warehouses, loading docks, parking facilities, and other commercial or industrial applications.
This field modification kit mounts to the operator’s limit mechanism so the auxiliary contacts track the primary open/close travel without affecting normal operation. Wire the contacts per your operator’s schematic to deliver dedicated signals for indicators or controls. Installation and adjustment should be performed by a qualified technician with power locked out, followed by verification of travel limits and a full safety test. Because compatibility varies by operator model and control logic, consult the LiftMaster operator manual or parts list for your unit to confirm that 71-909210MD is approved for use before ordering or installing.