Abstract: An off-highway vehicle systems simulator and control panel testing apparatus produces electrical signals that simulate the electrical signals generated by detectors on the vehicle when it is operating. The electrical signals are generated from four direct current power supplies and an AC frequency generator. The signals are directed to specific circuits within the control panels by a plurality of switches that essentially route the signals to specific pin locations on the control panel. The control panel is electrically coupled to the simulator by a harness having multipin plugs and mulitpin connector elements. Analog and digital monitors measure the output of the so treated panels, which is compared to outputs for correctly operating panels. Indicator lights are used to determine the status of the simulator and various circuits in the control panel.