Get your machines model and serial numbers, go to the Scag website, scroll down to operators manuals, click on it, find zero turn machines, a Scag Tiger Cub will be in the archived manuals area. Find you machine by model and serial number, download the manual. At the end of the parts portion there will be wiring diagrams.
Under the control panel close to the key switch is the engine cranking relay. This relay is grounded by the electronic control module when all the safety circuits have been correctly lined up for engine cranking. The safety circuit include the seat switch, left and right travel levers, parking brake, and the PTO switch in the off position. The engine cranking relay is a known frequent failure item.
There will be a remote starter solenoid if Briggs Intek/ELS powered, if other power, the starter solenoid will be mounted on the starter motor.