Honda BF15D BF20D Outboard Motors Shop Manual., Page 294Get this manual
BFI 5D-BF2OD bINSPECTION
Measure the resistance between the terminals and be sure that the measurements conform to the ranges shown in the table belowUse tester that is equivalent to or higher than the performance specified; Internal resistance: 20 QNDC, QNAC Be careful not to touch the metallic part of the tester probe with your body, otherwise correct resistance value cannot be obtained Read the tester manufacturer's operation instructions carefully before operation with testerFollow the instructions of the Service ManualBe sure the tester's battery is fully charged and check the meter before using the testera Use scale of an commercially available multimeter, and meter shows current flow from negative (-) to positive (+)The meter shows current flowing one way and not other the diode is good[I] Type with 6A charge coil