1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 43Get this manual
Stator Ohms Test (Alternator LightingCharging Coil) NOTE: Stator can be tested without removing from engine
Alternator.System Test (10 Ampere Stator)
1Check battery voltage at battery with engine running2If battery voltage is above 14.5-15.0 volts, replace voltage regulatorrectifierCheck condition of battery as overcharging may have damaged battery3If battery voltage is below 14.5 volts, charge battery; refer to "CHARGING DISCHARGED BATTERY" If battery can NOT be satisfactorily charged, replace battery
1Disconnect the three wire (stator harness plug)
2Use an ohm meter and perform the following testNOTE: 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'LlGHTING COIL
4If battery accepts satisfactory charge, check battery voltage while cranking engine; refer to "CHARGING DISCHARGED BATTERY"If cranking voltage is not acceptable, replace battery