Honda Outboards BF40A/BF50A Service Manual, Page 204Get this manual
HONDA BF35A45A
TRIM CONTROL UNIT (Power trimtilt type only)
Be sure the battery is in good condition before performing this test
[1] TRIM CONTROL UNIT
1) Check that there is :!: 0.1 of voltage between the and 81 terminals in the circuit shown to the right