The FSM has a procedure for testing it. Download the FSM from the home page of this site. You will need a Digital Volt Meter (analog will work, but DVM's are better/safer/easier). Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII