Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Brake/interlock has two functions, one is for start, the other is for the run circuit. Your run circuit is not complete. Brake switch may be bad, or the connections between it and the seat switch and pto switch may no be making the connection. Need to check the continuity between the switches, if brake switch does not help. age 31 in the operators manual linked below has wiring diagram/