1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 80Get this manual
CHARGINGSTARTING SYSTEM
Battery Charging System Tests
Testing The Battery Charging Coil
NOTE: Charging coil can be tested without removing from engine1Disconnect the charging coil leads2Use an ohm meter and perform the following test
NOTE: When measuring the resistance of 10 ohms or less using an digital ohm meter, if the correct measurement cannot be obtained, place the meter selector to lower resistance measurement