Merc 9.9

[Leaky pipes]

The engine won't shutoff at the key or lanyard,I had salt intrusion at the harness plug pin connection near the motor.I cut the the connector off and hard wired. Still did not shutoff.Although I cleaned the wires at the connection point they were black as far as I could cut them back .I'am guessing this corrosion could cause this??I'am also assuming the black w/yellow stripe wire would be the stop wire.??I replace the keyed ignition switch also as I had some sticking problems before.
Thanks