Generator cranks but will not start; fault light on, Code 11 displayed or flashed

Safety first: Turn OFF the generator at the control panel, open the main AC breaker to the load, and disconnect the battery negative cable before touching wiring. Standby generators can start automatically—disable auto-start per the manual.

• Check local start/stop switch: Inspect the switch on the genset for physical damage or sticking. Cycle it several times. If it feels loose or intermittent, it may be faulty.
• Inspect remote start wiring: Trace the remote start/stop harness from the transfer switch or remote panel to the generator control board. Look for pinched, chewed, or broken wires, especially near conduit entries and frame edges.
• Check connectors at controller: Remove and reseat the multi-pin connectors on the Onan controller (e.g., A1/J1, J2). Look for bent pins, corrosion, or moisture. Clean with electrical contact cleaner and reconnect firmly.
• Test start signal: With battery reconnected and using a meter, verify that the start input terminal on the controller receives proper DC voltage when a start command is given. If the controller never sees the signal, suspect the remote wiring or switch.
• If controller output is missing: If the start signal is present but the controller does not energize the starter relay, the control board may be defective and should be tested or replaced by a qualified technician.