2004 SR Johnson 2 Stroke 9.9, 15, 25, 30 HP Outboards Service Manual, Page 90Get this manual
ELECTRICAL TACHOMETER CIRCUIT TEST
TACHOMETER CIRCUIT TEST
IMPORTANT: The tachometer circuit is driven by the stator outputBefore proceeding, check condition of the stator and do the Stator Resistance Tests on p86Inspect all engine and boat wiring and make sure connectors are in good conditionDo the following tests if the tachometer does not operateSTEP Set peak-reading voltmeter to "POS" and "50 Check voltage at the battery Use this reading as the reference for battery voltageSTEP Check for battery voltage between the tachometer purple lead and black lead at the dash with the engine NOT running and the key switch ON If the voltmeter shows battery voltage, go to STEP If the voltmeter shows less than battery voltage, check the purple, purplered, and black circuits engine fuse, key switch, and the battery connectionsSTEP With the engine NOT running and the key switch ON, check for battery voltage between the instrument harness gray lead and black lead at the dash If voltmeter shows V, go to STEP If voltmeter shows any voltage replace rectifier