2006 Johnson SD 3.5 HP 2 Stroke Outboard Service Manual, PN 5006562, Page 41Get this manual
MAINTENANCE ANTI-CORROSION PROTECTION
ANTICORROSION PROTECTION
Sacrificial Anodes
Galvanic corrosion occurs in fresh or salt waterSalt, brackish, and polluted water can accelerate corrosion"Sacrificial" anodes are intended to protect the underwater metal components of the outboard from galvanic corrosionOutboards are equipped with sacrificial anodes
Testing ProcedureContinuity
Connect meter leads between engine ground and anode surfaceMeter lead to anode
The multimeter should indicate little or no resistanceIf resistance is high, check the following: Remove the anode and clean the area where the anode is installed Clean the mounting screws Install the anode and test againDR28873
3.5 Model 1Gearcase housing anode
Metallic Component Protection