A tractor park brake force sensing system includes a force sensor switch that is actuated if a tensile force applied to a linkage between a park brake lever and a park brake is adequate to compress a spring in the linkage a pre-specified amount as the park brake lever is moved to a park brake set position. A controller connected to the force sensor switch and to a tractor motion sensor turns on a solid indicator light if the force sensor switch is actuated, and flashes the indicator light if the park brake lever is moved to the park brake set position and the tractor motion sensor indicates the tractor is moving.