1972 Evinrude StarFlire 125 HP Outboards Service Manual, PN 4822, Page 93Get this manual
ALTERNATOR CIRCUIT CHECKS
Where To Look Cause What To Do UNDERCHARGED BATTERY BATTERY 1Defective battery or worn out battery 2Low electrolyte level 3Corroded terminal connections Check state of charge Add water Clean with wire brush and coat with petrolatum Tighten securely Check total current draw in circuit Troubleshoot (See page 7-12) Clean and tighten connections Check leads for defective lead insulation or connectorsStator leads are yellowCheck for worn through insulation and check diodes Disconnect rectifier leads and check each diode on HI ohms scale High reading on one check and no reading on another, diodes OK Zero reading both checks, shorted diode Infinite reading both checks, open diode ALTERNATOR Defective stator winding Connect ohmmeter between the two yellow leads at the alternator Connect ohmmeter from either yellow lead at alternator to ground OVERCHARGED BATTERY ALTERNATOR Extensive running without accessories Under capacity battery Turn on some accessories during extensive running 70 amp hrmin recommended Low OHMS Scale AMP stator .75 OHMS Result