Re: Peak reading tester
Sounds like you are checking battery voltage. You don't need a peak reading meter for that. You need the DC setting on a standard multi-tester. 2/10 of a volt DC drop between the battery and the "I" terminal on the tach will not affect tach operation. You have other issues such as a bad tach or a bad rectifier. The tach for an outboard counts pulses from the charging system which is an AC system. In the case of a Johnson the charging system has 12 poles which as the flywheel rotates creates six pulses with each revolution. It is those six pulses that the tach counts. Using this technique, the tach can be used on any engine whether it has one cylinder or a hundred -- as long as the tach can be set for the number of pulses/rev for that engine. The pulse or send signal from the charging system is the gray wire in the harness and it originates at the voltage regulator on the engine. If the engine isn't charging the battery, then the regulator is likely bad and it also accounts for why the tach doesn't work. Measure battery voltage with the engine off. Now start the engine and set rpm up to about 2000. If the voltage on the battery doesn't rise above 12.6 you have a bad charging system.
