2009 Yamaha F40 Outboard Service Manual, Page 124Get this manual
Electrical system
6Install the starter relay, and then connect the starter relay leads
Checking the neutral switch (tiller handle model)
1Disconnect the 10-pin coupler2Turn the engine start switch to "START," and then check the neutral switch for continuity at the shift lever positions F, N, and R
Checking the engine start switch
1Disconnect the 10-pin or engine start switch coupler2Check the continuityengine start switch for
OFF ON START