2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 259Get this manual
Electrical system
7Install the thermoswitch, and then connect the thermoswitch connectors
Checking the oil pressure switch
1Disconnect the oil pressure switch connector2Start the engine, and then measure the input voltage between the oil pressure switch connector (wiring harness end) and the groundCheck the wiring harness if below specification13
S6AG8110
Oil pressure switch continuity: Oil pressure switch Ground Engine condition Continuity Yes No