conehead 14 #1 Posted May 31, 2021 Good morning Wizards of Wheel Horse. I am trying to clean up the wiring on my 1988 312-8. Like others, all of the original wiring is gone, removed by previous owners. I acquired my WH last fall, it has run flawlessly since I bought it. I developed electical issues about 10 days ago and determined it was the ignition switch. I replaced the switch late last week (without researching which switch would be the correct one to install). I found an identical switch at Tractor Suppy and that's what I installed. The new switch contains the following connections, B, S, L, M & G. During the "reinstall" I discovered that there are no wires from the rectifier or the magnito (which might explain why the engine will not shut off now) to the ignition. None of this makes any sense to me because I have had no electical issues up until now. So I guess the question is, based on the wiring diagram from the most recent guide, can I follow the Charging, Gauge and Lighting Circuit descriptions without damaging my systems OR are previous posts from Duff (and maybe others) accurate that these diagrams are incorrect?? I am sure that I can correctly make the connection from the coil to the "M" connector on the switch thus solving the engine shut down, but I know that if I don't get the connection correct to charge the battery I'm going to have some future problems. Finally, I am neither experianced in small engine repair or engine/tractor wiring. Everything I have performed to date I have learned from this support group. At this point in my life, I follow directions well. Any guidance is greatly appreciated. Oh, also here is the current connections I have made to the ignition switch, B: Battery, S: Solenoid, L: Lights & G: Ground. I will be making the "M" connection today. Thanks to all who can help! Conant 1 Share this post Link to post Share on other sites
lynnmor 7,866 #2 Posted May 31, 2021 There are a number of ignition switches that look the same, M is for a magneto ignition and is used to short out the spark to stop the engine. I didn't look up what you need, but compare the letters and positions to the new switch. 2 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,534 #3 Posted May 31, 2021 This should be the correct wiring diagram for the 1988 312-8. Click on the picture for a quick look. The only odd thing is the rectifier output is connected to the ACCESSORY switch terminal The accessories are connected to the RECTIFIER switch terminal. They are reversed and reported that this is correct. Garry 1 Share this post Link to post Share on other sites
conehead 14 #4 Posted May 31, 2021 Thanks Lynnmor & Gary. Gary, Just to be clear, based on your response, I should consider the current wiring diagrams as presented in the guide as accurate and correct? That I should connect the rectifier to the Accessory terminal and then connect the headlights and gauges to the Rectifier terninal? If this is correct then, can I use the current ignition switch and run the rectifier into the Accessory terminal along with the lights and gauges without causing any damage? Pardon my ignorance. Thanks, Conant Share this post Link to post Share on other sites
biged77 113 #5 Posted May 31, 2021 I have three 400 series tractors that are wired according to the corrected wiring diagram but seemingly backwards (R to accessories and A to the regulator). They work fine. Thanks to Garry for these corrected and color coded diagrams. 1 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,534 #6 Posted May 31, 2021 1 hour ago, conehead said: Thanks Lynnmor & Gary. Gary, Just to be clear, based on your response, I should consider the current wiring diagrams as presented in the guide as accurate and correct? That I should connect the rectifier to the Accessory terminal and then connect the headlights and gauges to the Rectifier terninal? If this is correct then, can I use the current ignition switch and run the rectifier into the Accessory terminal along with the lights and gauges without causing any damage? Pardon my ignorance. Thanks, Conant You don't have an R terminal? Your switch terminal locations should match the illustration above of the 103991 switch. Garry Share this post Link to post Share on other sites
conehead 14 #7 Posted May 31, 2021 (edited) 29 minutes ago, gwest_ca said: You don't have an R terminal? Your switch terminal locations should match the illustration above of the 103991 switch. Garry Hello Garry, I do not have an R terminal. The switch I have contains the following terminals: B, S, L, M & G. This is the switch that came on the tractor. Also, all of the original wiring is gone, rewired by previous owners. Thanks, Conant Edited May 31, 2021 by conehead additional backstory Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,534 #8 Posted May 31, 2021 Can only guess the switch you have is one of these. Notice some apparently do not have the terminals properly identified. The only way to be sure is to use an ohm meter to compare to the switch function charts. First difference is the number of key positions. You should have 3 key positions. If you can verify the switch we can compare the wiring diagrams to see how they did it. Click on the pictures The 116338 was used on the 1992 312-8. Garry Share this post Link to post Share on other sites
conehead 14 #9 Posted June 1, 2021 Thanks Garry, Will do some investigating this week. Thanks for your time and patience with this. Conant Share this post Link to post Share on other sites
