2009 Yamaha F40 Outboard Service Manual, Page 107Get this manual
ECM coupler layoutChecking the electrical component
Checking the electrical component
Checking by use of YDIS
When checking the TPS, ISC, high-pressure fuel pump, fuel injector, or each sensor, use the YDISWhen deleting the diagnosis record in the YDIS, be sure to check the time that the trouble codes were detectedWhen checking the input voltage of part, the coupler or connector must be disconnectedAs result, the engine ECM determines that the part is disconnected and trouble code is detectedTherefore, be sure to delete the diagnosis record after checking the input voltageYDIS (CD-ROM, Ver1.32): 60V-WS853-05 YDIS (KIT): 60V-85300-05
When testing the voltage between the terminals of an electrical component with the digital tester, do not allow any of the leads to touch any metal partsIf touched, the electrical component can be short-circuited and damagedTo check the electrical components or measure the peak voltage, use the special service toolsA faulty electrical component can be easily checked by measuring the peak voltageThe specified engine speed when measuring the peak voltage is affected by many factors such as fouled spark plugs or weak batteryIf one of these factors is present, the peak voltage cannot be measured properly