2000-2005 Yamaha F40B Outboard Service Manual, Page 448Get this manual
ELECTRICAL COMPONENTS ANALYSIS
When measuring the peak voltage, set the selector to the DC voltage modeMake sure the peak voltage adaptor leads are properly installed in the digital testerMake sure the positive pin (the "+" mark facing up as shown) on the peak voltage adaptor is installed into the positive terminal of the digital testerThe test harness is needed for the following tests