MT372D Electric quit

[Flyndogg]

Hello all,

I was using my ol' Mitsubishi MT-372D when it just quit (like a stall). All 3 lights (chg, temp, oil) were not on, usually they are when the engine quits and the ignition key is still on. I went to restart and I got absolutely nothing. No electric what so ever. The battery is good (with good ground), 15 amp fuse is good and no wires disconnected or broken...I've chased them all with a multi-meter. Any ideas out there? Maybe Voltage regulator or alternator...but why would that make the engine quit while it was running? Thanks for your time!

Sean

 

[Republic of Texas]

Check connections, especially at the starter.

You were using the tractor & shook a wire loose. It may not appear loose, so unplug & replug every connection that you can & access easily.

 

[Dave M7040]

Don't know if your tractor has one but good chance: Fusible Link

A glorified piece of wire that acts like a one time fuse but with insulation designed to let the metal wire inside melt apart and yet the insulation, although it will look beat up, will stay in place.
Usually they are in the tractor to protect the entire electrical system.
This link will give you a good explanation on how they work.
Never replace a blown one with a piece of wire or the reason it blew in the first place could happen again and start a fire because your replacement wire is not designed to melt down safely

Weather Pack Environmentally Sealed Connectors | Weatherpack Terminals and Seals | White Products Cleveland Ohio

Often they are at the big battery terminal of the starter and are in a wire feeding all power to many different circuits of the fuse block.

I have posted some pictures of the links, what they look like, and how they are described in a parts list and in an owners manual.
I know two of the pictures are for a Kubota B7800 but Kubota did not invent them and your MT's owners manual or parts list may have one shown.
The first picture is a small loop of wire, sort of an in and then out wire with a plastic connector so it can easily be removed from the wiring harness and replaced.
The third picture shows a similar design that plugs into the side of the fuse block.

If you are certain both ends of both the power and ground battery cables are bright and shinny, remove and check, no just looking and presuming, and there is no power anywhere to
turn on lights for example then suspect a fusible link.

Your question, why would it quit when running?

Could you have an electric pump inside the fuel tank to feed the injection pump? Many tractors do.
No power and almost instantly the tractor engine stops dead.

With your multi meter is there power anywhere on the key switch?
If no then again suspect a fusible link

Dave M7040

 

[RNeumann]

When you say chased them are you reading voltage ohms? We are all thinking the same thing with a connection. Do you have voltage at the starter? Do you have voltage at the fuse panel? Do you have voltage at the ignition switch? If you have voltage those 3 places check the resistance from the battery to those 3 places. That should be a good start.

If you don't have power to one of those places the fusible link is a good point. It's hard to tell it apart from regular wire and it typically doesn't show that it has failed.

 

[Dave M7040]

Flyndogg

Since you have a multi meter try using it as shown in this troubleshooting guide from DENSO who are a big manufacturer of starters, alternators etc

http://densoautoparts.com/sites/default/files/tech-tips/DENSO Starter troubleshooting tips.pdf


Others I have suggested this technique to find their problem if they carefully follow its steps sequentially and don't start jumping around in the process. It also avoids cleaning the ends of battery cables which did not need it.

If you have questions about any part of it plse ask.

Dave M7040

 

[Dave M7040]

Flyndogg
Me again.
I found a wiring diagram on line and studied it.
Although I don't understand the design in the sense that there is only one 15 amp fuse, no sign of a fusible link and yet the alternator is rated at 35 amps.
I am puzzled but encourage you to go through the Denso stuff as step one.
Battery power goes to the starter thought the heavy battery cable. From that terminal a black wire with possibly a white stripe goes to the starter switch and the alternator.
Power from the starter switch goes to the regulator and then to the 15 amp fuse.
Follow this black white stripped wire with your voltmeter to see where there is suddenly no voltage. One wire of the voltmeter on the battery negative terminal and the other touching various terminals along the route I described.
Dave M7040

 

[Republic of Texas]

Flyndogg

Since you have a multi meter try using it as shown in this troubleshooting guide from DENSO who are a big manufacturer of starters, alternators etc

http://densoautoparts.com/sites/default/files/tech-tips/DENSO Starter troubleshooting tips.pdf


Others I have suggested this technique to find their problem if they carefully follow its steps sequentially and don't start jumping around in the process. It also avoids cleaning the ends of battery cables which did not need it.

If you have questions about any part of it plse ask.

Dave M7040

I'm on mobile, but the link says Page Not Found.

 

[Dave M7040]

Dont know why it does not work for you, I checked what was on the forum and the link came right up.
Google: DENSO Starter troubleshooting tips

If should be at or near the top of their search list.

Dave M7040

 

[oliver28472]

This tractor should run with the battery disconnected so there is another problem that made it cut off, even if something is wrong with the electrical system. There is no shutoff solenoid.

 

[Dave M7040]

This tractor should run with the battery disconnected so there is another problem that made it cut off, even if something is wrong with the electrical system. There is no shutoff solenoid.

Oliver
You obviously know his particular model of tractor with your comments on it running with no electrical like all old diesels. I learned the hard way on a cold winter night that my tractor would no longer run with the charging system kaput, the battery run to almost dead by all my extra lighting, because I had replaced the mechanical fuel pump with an electrical one.

I re read the original post and what i cannot reconcile is the fact that, after the engine stalled, everything was dead when a restart was attempted.

Am I overlooking the obvious?

Dave M7040

 

[orezok]

I would suggest that you use a test light in addition to you VOM. A blown fuse can still pass voltage, but insufficient amperage to do anything. If a 12 volt test light works, you have both. Ask me how I know.

 

[oliver28472]

Here is a link to a wiring diagram to a 370. Couldn't find one for a 372 but I think they are pretty close to the same. Satoh Parts