2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 87Get this manual
ELECTRICAL CHARGING SYSTEM TESTS STEP 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 ONcheck 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, disconnect rectifierregulator gray lead from engine wiring harnessIf voltage disappears, replace rectifier regulator If voltmeter still shows voltage, disconnect pump's 4-pin connector from engine wiring harnessIf voltage disappears, repair pump's connector or replace pump's circuit board If voltmeter still shows voltage, repair or replace boat's instrument harness or engine wiring harnessSTEP With the engine running at 1000 RPMcheck for voltage between the instrument harness gray lead and black lead at the dash If voltmeter shows v, go to STEP If voltmeter shows less than V, leave the voltmeter connected to the boat harness gray lead and got to STEP If voltmeter shows more than V, replace the tachometerSTEP With the engine NOT running and the key switch ONcheck for battery voltage at the terminal board purple connection If voltmeter shows battery voltagereplace the rectifierregulator If voltmeter shows NO battery voltage, check instrument harness and engine harness purple and purplered circuits, engine fuse, and key switchTachometer Circuit Test 1Purple lead 2Black lead 3Graylead 4Purple lead terminal board connection 5OMS pump harness 6Purple lead, not used on all regulatorrectifiers