2003 Johnson ST 6/8 HP 4 Stroke Outboards Service Manual, PN 5005471, Page 63Get this manual
ELECTRICAL CHARGING SYSTEM
Charging System Check Chart
Where to Look Cause
Battery defective or worn out Low electrolyte level Battery Terminal connections loose or corroded Excessive electrical load Connections loose or corroded Wiring Stator leads shorted or grounded Circuit wiring grounded Damaged stator windings Alternatorstator Weak flywheel magnets Damaged stator leads Rectifier Inoperative rectifier Perform ohmmeter tests Stator resistance test Perform ohmmeter tests Perform ohmmeter tests Perform running output tests Perform ohmmeter tests Perform rectifier tests Stator resistance test Running alternator output test Stator resistance test Rectifier resistance tests Clean and tighten Evaluate accessory loads Running alternator output test; Stator resistance test
Procedure
Check condition and charge Add water and recharge
Reference