Please Help! My B7800 is blowing a fuse, shutting down. Tractor stuck outside :-(
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/ Please Help! My B7800 is blowing a fuse, shutting down. Tractor stuck outside :-(
#12
So, I have the tractor fixed for now. Thank you all who responded to the question. The brief description of the "repair" went like this. I spent two thankless days trying to find the problem standing outside in the 0F weather 20ft from my barn, where the tractor broke down. Eventually with the help of a friend/neighbor we towed the tractor to his heated garage.
As it turns out the 5 Amp fuse connects to about a dozen or so things on the tractor. It was a royal pain in the aft end. First we checked the key switch, the wires to all the safety switches, replaced the fuel solenoid and the solenoid control relay and even took off the fuse box to look for a chaffed wire. I also took off the dashboard to look for mouse damage.
After not being able to find an actual short I decided to hot-wire all the safety switches to eliminate any potential problems. Yes. I could have tested the switches with a multimeter, but they are and absolute nightmare to get to, so I went the hot wire route.
At that point I decided to see what it does if I try to start it. The tractor would not start, but it didn't blow the fuse anymore. A rather happy accident lead to the discovery of a connection problem. The key was accidentally left on, and in the process of checking the rest of the fuses I jiggled the fuse box and heard a faint click from the relay that controls the fuel solenoid. That gave me the idea that there is a loose connection in the fuse box itself.
And, sure enough after bending the connections a bit in the fuse box, the relay stayed on and after I reconnected the solenoid, it also worked, and the no fuse blew. The tractor started up and ran like it always have.
Next, I opened a beer, that I happily drank while we put the machine back together. (I reconnected ALL of the safety switches too)
I drove the tractor home and parked it in my unheated garage. That night the temperature hit a balmy -13F. In the morning, after two hours of block heater it started right up and ran like the champ it has been for years.
To be honest, I am not certain if I did find the original problem, or it just went away in the process of moving the wires as I tested them with the multimeter.
The local dealer did give me the wiring diagram, that I used a lot. Coincidentally the wiring diagram for the B7800 was posted in a separate thread so I am including a link to that, in case some other poor bugger will need it in the future. Look for it in reply #16.
As it turns out the 5 Amp fuse connects to about a dozen or so things on the tractor. It was a royal pain in the aft end. First we checked the key switch, the wires to all the safety switches, replaced the fuel solenoid and the solenoid control relay and even took off the fuse box to look for a chaffed wire. I also took off the dashboard to look for mouse damage.
After not being able to find an actual short I decided to hot-wire all the safety switches to eliminate any potential problems. Yes. I could have tested the switches with a multimeter, but they are and absolute nightmare to get to, so I went the hot wire route.
At that point I decided to see what it does if I try to start it. The tractor would not start, but it didn't blow the fuse anymore. A rather happy accident lead to the discovery of a connection problem. The key was accidentally left on, and in the process of checking the rest of the fuses I jiggled the fuse box and heard a faint click from the relay that controls the fuel solenoid. That gave me the idea that there is a loose connection in the fuse box itself.
And, sure enough after bending the connections a bit in the fuse box, the relay stayed on and after I reconnected the solenoid, it also worked, and the no fuse blew. The tractor started up and ran like it always have.
Next, I opened a beer, that I happily drank while we put the machine back together. (I reconnected ALL of the safety switches too)
I drove the tractor home and parked it in my unheated garage. That night the temperature hit a balmy -13F. In the morning, after two hours of block heater it started right up and ran like the champ it has been for years.
To be honest, I am not certain if I did find the original problem, or it just went away in the process of moving the wires as I tested them with the multimeter.
The local dealer did give me the wiring diagram, that I used a lot. Coincidentally the wiring diagram for the B7800 was posted in a separate thread so I am including a link to that, in case some other poor bugger will need it in the future. Look for it in reply #16.
Last edited:
Leejohn
Elite Member
Where is the link? That reply #16 didn't get it.
AWSubie
Platinum Member
How about this image?
/ Please Help! My B7800 is blowing a fuse, shutting down. Tractor stuck outside :-(
#16
I will try it again. Hopefully this works.
http://www.tractorbynet.com/forums/...6-b7800-alternator-upgrade-2.html#post4953390
Leejohn
Elite Member
Got it, thanks.
tysmobiletractor
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So, what was it?
Henro
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