In Reply to: 1940 9N starter relay question posted by Serge on January 22, 2018 at 18:44:29:
6-volt/positive ground or a 12-volt conversion? NO, the starter button does not stay engaged to keep the tractor running, if that is what you mean. Also, the Ford 9N and 2N tractor electrical starters did not have a solenoid on the starter, if that is what you mean. Their units have but one wire only. Some guys think the round-can cutout located behind the dash is the starter solenoid but they'd be wrong. The 9N/2N starter has the one wire going from the unit to one side of the Neutral Safety Interlock Switch (Button) beginning at s/n 12500. The other terminal connects a wire from it to the NEG terminal on the battery if original 6-volt/positive ground. When you turn the key and all you get is a 'clicking' sound, chances are great it is because you have a dead or badly discharged battery. You need a good, fully charged battery in order to crank the engine over. How old is yours? 6 volt or 12 volt system? Your battery must sustain a charge under load, and that means not just slapping a battery charger on it overnight. You need it tested for specific gravity with a hydrometer, or, just take it to your trusty local starter/alternator shop and they will bench test it with the proper test equipment, usually for free. Do you have the essential 9N/2N owner manuals? If you have a 6-volt/positive ground system, you are not jumping it correctly for one. Get a copy of Bruce(VA)'s 75 Tips for N Owners ((see HOW-TO's forum) downloaded for shop reference. Seek WIRING PICTOGRAMS by JMOR (see HOW-TO's forum)for the correct way to wire these old N's regardless if 6 volt or 12 volt. Excessive cranking with failure to start will soon foul your plugs. Pull one and analyze. If wet, do not discard, pull them all and replace with fresh dry ones, or take a flame to burn off excess fuel, gently clean with a toothbrush or brass wire brush, recheck gap, .025" on front mount systems, and reinstall. Your problem sounds like electrical, but check for fuel flow once you get battery fully checked and charged and new plugs installed -again, see Bruce(VA)'s tips. I do not see anywhere in the F-04 Manual where it calls the 9N/2N starter button a relay.
FORD 9N/2N TRACTOR OWNER ESSENTIAL MANUALS: