# MF 4253 Blows Stop Fuse



## penright14 (Aug 6, 2013)

Let me say first, I am a city boy, who loves to work on cars. Forgive me if I use the wrong terminology.

I helped my bother-in-law last night work on his MF 4253. It was blowing the Stop fuse after running about 10 minutes. Then it would blow the fuse immediately until it set for a while. If we pulled the fuse and measured the non-bus side to ground it had 0 ohms (dead short). So we traced the wire out of the cab though firewall, to a plug. When we disconnect the plug the short at the fuse block disappeared. So then we trace the wire through the engine compartment. It branched into two different paths. One went down to a plug that had what we guess is a ground wire. It was connected to a sensor on the injector pump. I measured the resistance of switch (two pins) and it showed a short. So I am guessing it was some sort of switch sensor. Then the other lead went to a sensor screwed into the water pump/ pump area. I am assuming some sort of temperature sensing. Coming off of it was another orange wire that after tracing it out, did not seem to be plugged into anything. But after pulling it up to look at it, the orange wire at the firewall plug now read 2k ohms. Put it all back together and it ran all the way to finish the plowing.

Can anyone explain how this works? 
What the purpose of the circuit is? 
If the injector pump sensor is a switch, and it is connected to a line voltage, would it not blow the fuse? 
Could the non-connected line have been somehow touching ground and that is what blew it after some certain temperature?
Should the non-connected wire be connected?

[added]
I found this about a 451, sounds familiar, is a 451 and 4253 enough in common? http://www.tractorforum.com/f50/451-blows-fuse-14152/

Please help my curiosity and besides I want to make sure we did not defeat some safety circuit. Thanks a bunch in advance.


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