1990 Johnson Evinrude "ES" Cross V 88 thru 115, 150 thru 175, P/N 507874, Page 36Get this manual
AnodesTesting and Replacement Erosion or disintegration in salt or brackish water indicates the anodes are performing their functionThe anodes should be inspected andor replaced at intervals or corrosion of the engine will increase If any anode has been reduced to two thirds its original size (one-third eroded) it must be replaced! To increase the duration of the anodic protection, the starboard stern bracket (on some models) is drilled to accept an additional anode
E.I to low ohms scaleConnect one lead of the ohmmeter to