Bcmedic85 12 #1 Posted April 16 Ok you guys are the experts this is my first wheel horse mower I’ve searched the forums here seems like no one has my specific issue.. my mower is a 90 something 312-8 model number is 73362, serial number is 4900916. My issue seems to be blowing the 25amp fuse happens about 10 minutes or so after engaging the manual pro while mowing. I can put a new fuse in and same thing happens. Also after the fuse has blown if I jump the starter solenoid and get it running if I try to engage the pto the motor will die but if I disengage it fast enough it will stay running. The seat sensor is already by passed on the mower, the pto and clutch safety switches are still in place and seem to be operational since with a good 25amp fuse everything will work normally until after mowing for a period of time. I’ve checked all the wires so far have not found any bare spots. Could it be a bad or going bad ignition switch? If so how would you test it? Or does anyone else have any thoughts ideas I’m not sure what else it could be. Share this post Link to post Share on other sites
Bcmedic85 12 #3 Posted April 16 22 minutes ago, gwest_ca said: Thanks for the wiring diagram looks like the only thing that could be blowing the 25amp fuse would be a bad ignition switch I’m guessing or rather one that is going bad since it starts fine with a good fuse in it 🤷♂️ Share this post Link to post Share on other sites
elcamino/wheelhorse 9,066 #4 Posted April 16 I think you have a wire that is shorting out and blowing the fuse. 1 Share this post Link to post Share on other sites
squonk 38,980 #5 Posted April 16 (edited) It could be the switch has a short to ground. Does the tractor shut off at the exact same time as the fuse blowing? Tractor is old enough. Replace the switch. If it still does it there is a wire chafed somewhere. The wires going to the disconnected seat switch are good candidates for chafing. Edited April 16 by squonk 1 Share this post Link to post Share on other sites
Bcmedic85 12 #6 Posted April 16 14 minutes ago, squonk said: It could be the switch has a short to ground. Does the tractor shut off at the exact same time as the fuse blowing? Tractor is old enough. Replace the switch. If it still does it there is a wire chafed somewhere. The wires going to the disconnected seat switch are good candidates for chafing. Yes the tractor dies the exact same time the 25amp fuse blows while the pto is engaged. After it dies I can jump the solenoid and it will stay running as long as I leave the pto disengaged, attempting to engage it instantly kills the motor again once the 25 amp fuse has blown. I’m leaning towards replacing the ignition switch and see what happens checked the plug and wires going to the switch they seem to look fine. Share this post Link to post Share on other sites
Bcmedic85 12 #7 Posted April 17 Update brand new ignition switch and now as soon as I turn the key to start the fuse blows Share this post Link to post Share on other sites
squonk 38,980 #8 Posted April 17 Did you get a magneto switch? 1 Share this post Link to post Share on other sites
Bcmedic85 12 #9 Posted April 17 Figured out the problem kinda 2 problems combined into one. Probably couple months ago I put a new solenoid on it and must have had some wires crossed then the ignition switch finally gave out completely. I had to change the wire spots around in the factory plug to match the new ignition switch I got from the store because it was completely different compared to the original one. Ground was completely opposite as well as magneto and battery. Fixed that and swapped the solenoid wires back around and mowed the yard didn’t blow a single fuse. I’m just kinda shocked I had the wires mixed up and it was still running up until that point. The horse is back in business now! Thanks everyone for the help the wiring diagram was a life saver! 1 Share this post Link to post Share on other sites
