Honda Outboards BF40A/BF50A Service Manual, Page 203Get this manual
HONDABF35A45A NOTE Be sure the battery is in good condition before performing this test
Check that there is battery voltage between the ground cable BI and the motor output side -and Bu in the circuit shown to the right
POWER TRIMTILT SWITCH (Power trimtilt type only)
Attach the tester lead to each terminal and check for continuityThere should be continuity between the terminals marked with circle in the table below