MF 2300

[jminpa]

Hello, I have a mf gc2300. Recently while using the tractor I shut it off and it would not restart. The 40A slow blow fuse to the starter was blown. I could not find a short in the wiring on either side of the 40A fuse with a continuity tester. I checked all of the wiring visually on the tractor looking for a short or bare wire. I replaced the fuse and used the tractor all day with no problem, on and off the seat but never shutting the tractor off. When I parked the tractor I shut it off and did a restart with no problem but i noticed that the fuel gauge was quickly going to zero and the lights no longer worked, then the tractor would not shut off.
I shut the tractor off with the plunger switch on the fuel pump and found the 40A fuse blown again. Again I could not find a short with a meter. I then removed the ignition switch and found the back with the wires completely corroded. I have read most of the posts on this site and understand that the ignition is a common problem. I am leaning toward the switch shorting causing the fuse to blow as it happens during a starting operation.
The question is, Has anyone had luck cleaning the wire corrosion and reusing the switch or is the problem internal to the switch? I am trying to avoid buying a new switch.
Also, I think that I have determined that the wiring diagram is inside the repair manual and not in the operator's manual. Can anyone confirm that the wiring diagram is in the repair manual and if so, is the diagram readable? The diagrams that i have found on the internet are unreadable when i zoom them enough to be able to follow the wiring. It looks like the diagram may have a box at the switch location showing what connections should happen at each switch position.
Any help appreciated,
thanks

 

[loulblades]

Hello,

Unfortunately my tractor is normally stored outside and the tether for the plastic ignition switch cover broke early on. I figured the way the key is made, leaving it in all the time would keep water out of the switch. It did last about 15 years. Recently I did have to replace the switch because mine was corroded and would pop fuses or just not work. I didn't use an MF switch and had to make some mods to get it to work.

My operator manual has the wiring diagram near the middle but I took a picture. Hopefully it's legible.

Lou

 

[jminpa]

Thanks Lou,
I am going to try to clean up the switch and cover it in dielectric grease before I order a new switch.
The diagram that you provided is the most readable that I have seen so far.
JM

 

[jminpa]

I reinstalled the cleaned ignition today. I turned the key to on, the dash lit up as normal, i could hear the fuel pump, i turned the ignition off and heard the injection pump delay click off. I then got on the seat and turned the key for glow plugs then turned switch to start. the engine started to turn over and blew the 40a slow blow main fuse again.
Then i removed the 40a fuse from the alternator to isolate from the 40a fuse to the starter. i didn't turn the key for glow plugs but went right to start while standing beside the seat and had the same result, the motor tried to turn and blew the 40a fuse.
The ignition seems to have the correct output through all of the switch positions.
The starter relay seems to be ok because it lets the starter try to start, and i think that a problem with the safety switches would blow the smaller fuses in the fuse panel.

 

[loulblades]

I looked at the schematic I sent to refresh my memory.

Other than the smaller fuses, the 40 Amp fuse's main point is to feed the starter and the glow plugs.

So if you have confidence in starter, I would check resistance across the starter when cold and hot also to ground. The glow plugs resistance can also be checked but I don't recall what it should be. I believe there is a connector on top of the engine to disconnect the glow plugs. Keep in mind the glow plugs are active when starting. Disconnect battery and check resistance to ground with ignition switch off and on.

When my ignition switch crapped out and the contacts rusted out, the glow plug pin wire on the switch would short to ground sometimes.

Hope this helps.
Lou

 

[jminpa]

Lou,
I feel pretty good about the starter, From what I have read a starter failure would be unusual. The machine has a little over 500 hrs , i think.
I think that I measured about 48K ohm through the fuse holder back to the starter to ground cold.
I was not leaning toward a glow plug failure because the fuse blows when the starter tries to roll the engine. My Manual has a table for the ignition switch connections at different key positions. #30 seems to be the power to the switch and is only connected to #19 with glow plugs. when you go to start wires 30,17, AC and 50 are connected but not glow plugs so I kinda of ruled out the glow plugs?
When the fuse blows i tried to find a short to ground through the fuse holder back toward the starter and toward the ignition switch but have found nothing.
I will try to get some resistance measurements as soon as i can.
To make things more challenging, this tractor has a loader so getting the panels off on the starter side would be more work. I don't want to disassemble to get to the harness from the fuse to the starter unless i was seeing a short in this area.
One more thing, The fuses that have been used come from advance auto and look exactly like the one that failed originally but none say slow blow on them anywhere. And the description doesn't mention anything about slow blow. The advance auto part is a little fuse brand and little fuse has not been helpful to let me know if this part is a slow blow fuse.
My nearest MF dealer is 1.5 hrs away.
Thanks Again,
JM

 

[loulblades]

Note that 17 and 19 are shorted external to the switch so glow plugs are active during starting.

Lou

 

[jminpa]

Note that 17 and 19 are shorted external to the switch so glow plugs are active during starting.

Lou

Lou, I see what you mean.
My schematic is a little different than yours, probably due to s/n. my s/n is JPA20652.
The schematic in my operators instruction book is a bit confusing. the drawing shows two different fuse numbers for the starter and alternator but when you follow the two numbers back to the drawing key they are both 40A. And The page in my book just before the schematic says that there is a 60A SB at the alternator.
Do you think that the starter relay has any thing to do with the problem or is it protected in some other way?
thanks again.
JM

 

[loulblades]

Looks like you found your schematics, unfortunately I am unable to clean the image enough to read yet. I will work on it more.

Lou

 

[jminpa]

Lou,
Yes I found a manual that I didn't think that I had. I will try to post a better image of the schematic.
Thanks
JM

 

[jminpa]

Looks like you found your schematics, unfortunately I am unable to clean the image enough to read yet. I will work on it more.

Lou

Lou, 2nd attempt at schematic upload.
JM

 

[loulblades]

Been tied up lately. Will take a look.

Lou

 

[jminpa]

Been tied up lately. Will take a look.

Lou

 

[jminpa]

Same here. A couple other breakdowns had to take priority.
I plan to get back to it this weekend.
JM

 

[jminpa]

I removed and cleaned all of the connections to the starter. I only measured 10.5v to the glow plugs, the battery showed 12.3v. The tractor started, I took the tractor to Advance auto. They said that the starter and battery are good but the tractor would not shut off, I assumed that the fuse blew and i shut it off manually but then i was able to restart? I went home and the fuse blew when i tried to start. Of course the tractor is not stored where I live so as I was driving home i thought that if I can measure 12v going into the ignition and only 10.5v going out to the glow plug wire then the switch could be the problem?
JM

 

[loulblades]

I think this may have been mentioned before, but do you have any way to measure current?
A current clamp-on feeding a multi-meter is easiest (IMHO). You don't have to put it in the circuit.
Also most multi-meters do not have the capability to measure something approaching or exceeding 40 amps.
You could use a shunt resistor (low resistance, high power) but that means putting it in series (removing wires). Also since Radio Shack isn't just around the corner anymore (at least not where I live), you would most likely have to order it. There are plenty of ohm's law calculators on line to figure the best one.

Lou

 

[jminpa]

I think this may have been mentioned before, but do you have any way to measure current?
A current clamp-on feeding a multi-meter is easiest (IMHO). You don't have to put it in the circuit.
Also most multi-meters do not have the capability to measure something approaching or exceeding 40 amps.
You could use a shunt resistor (low resistance, high power) but that means putting it in series (removing wires). Also since Radio Shack isn't just around the corner anymore (at least not where I live), you would most likely have to order it. There are plenty of ohm's law calculators on line to figure the best one.

Lou

Lou,
I do not have a DC current clamp. I was re-checking some voltages and testing the glow plugs when I noticed smoke coming from the bowels of the tractor. I started removing panels and parts and tracing the glow plug power wire under the motor until i found the short.
The short was at the metal spring steel that wraps around all of the wires holding them to the motor. The vibration had worn through the rubber coating on the spring steel and through the harness loom and then through the glow plug power wire which seemed to have a very tough teflon insulation. I made a repair to the glow plug wire.
I also replaced the ignition switch because at least once the tractor would not shut off while not having a blown fuse and the switch was very corroded.
That was a real head scratcher. The tractor seems to be back to normal.
Thanks for all of your help.
JM

 

[loulblades]

Lou,
I do not have a DC current clamp. I was re-checking some voltages and testing the glow plugs when I noticed smoke coming from the bowels of the tractor. I started removing panels and parts and tracing the glow plug power wire under the motor until i found the short.
The short was at the metal spring steel that wraps around all of the wires holding them to the motor. The vibration had worn through the rubber coating on the spring steel and through the harness loom and then through the glow plug power wire which seemed to have a very tough teflon insulation. I made a repair to the glow plug wire.
I also replaced the ignition switch because at least once the tractor would not shut off while not having a blown fuse and the switch was very corroded.
That was a real head scratcher. The tractor seems to be back to normal.
Thanks for all of your help.
JM

Excellent. Glad to hear it. Always feels good to solve a problem...even more so if it is a perplexing one.

Lou