Larger lawn tractors contain electric motors in starter system. Output shaft of electric motor in such a system connected to gears that engage flywheel. Spinning motion of electric motor’s armature transferred through gears to flywheel and engine crankshaft.
The starting system also has a starter cut-out relay which protects the starter motor during engine operation. After the engine has started, the tachometer control unit sends current to the starter cut-out relay. The relay switches off, interrupts the current flow to the starter motor, and the starter ceases to operate.
The following schematic illustrates the TGB Blade 250 ATV . The starting system consists of shift gear control unit, main switch, starter motor, starter relay, starter switch, and change switch. (click image to enlarge)
First interlock system to troubleshoot is recoil start system that has electronic ignition module. If engine won’t start with safety interlock conditions met, disconnect wires between safety switches and module. Replace wires with jumper wire that will complete safety circuit as if all wires were good and switches were closing. Then try to start engine. If engine starts with jumper wire in, check entire safety circuit for electrical continuity, and make sure switches are closing properly. If engine won’t start with jumper wire in, disconnect wire between ignition module and engine magneto. Try to start engine. If engine will start now, replace ignition module.