1993 Johnson Evinrude "ET" 40 thru 55 Service Manual, P/N 508283, Page 297Get this manual
Cranking Discharge Met hod 1Check battery voltage If voltage is greater than 12.5 volts, go to Step If voltage is less than 12.5 volts, go to Step 32Separate the ignition charge coil connector(s)Crank engine in short bursts until battery voltage is less than 12.5 voltsCheck battery voltage with key in the "Off" position Disconnect engine battery cables before proceeding with this check
3Connect to 40 amp ammeter in series between the rectifierregulator red lead and the battery side of the starter solenoid4Reconnect the engine's battery cablesReconnect the ignition charge coil connector(s)The rectifierregulator requires battery voltage on the purpie lead to operateBefore proceeding, verify battery voltage at terminal strip purple leads when key is ON 5Start the engine and run it at approximately 4500 RPM The engine's ammeter should indicate nearly full output12 ampsAs the engine continues to run at 4500 RPM, the voltage should stabilize at approximately 14.5 volts and the alternator output should begin to decrease If the engine's ammeter doesn't indicate the above, check stator condition before replacing rectifierregulatorTachometer Circuit 1Ifthe VRO "no oil" warning signal is in question or ifthe boat's tachometer is not workingtest the tachometer circuit2Verify that all wiring and Amphenol connectors are in good condition3Set peak reading voltmeter to