MT 372 dummy lights

[shags-72]

I found 2 broken wires on my tractor. 1 on the alternator plug and the other from the regulator plug. I fixed those and now after I start it if I turn the switch to off the charge light comes on. I thought about this and it seems like it should do this as it would indicate that you weren't charging your battery while running the tractor. Buuuut I really don't know if this is as designed. Anyone know about this? Thanks


Brad

 

[Ilikeurtractor]

The short answer is no, the charge light should not be on if the key switch is in the off position. When the switch is off power to the indicator lights is supposed to be disabled. You'll need to go through the wiring diagram to see what is going on with your wiring.

 

[shags-72]

I did not change position of the wires so what else could it be? The regulator I think is bad as it is outputting 18v with the key on. This is why I don't want to have the key on while running. I looked at the diagram and the lead from the regulator to the light is straight to it. No idea where to go from here.

 

[Ilikeurtractor]

It's probably the regulator then. It shouldn't put out more than about 14 volts DC. I need to study the wiring circuit for the alternator and regulator every time I have a problem with it (which has only been 2-3 times total on several different tractors) so I don't remember all the details. If I remember the field part though, it should only be energized when the key is on. The alternator is connected directly to the battery via the starter lug so it must be backfeeding through the regulator to the light. I'm not sure what the exact condition is that is causing your problem. I have seen one of the solenoids in the mechanical regulators have an open circuit which creates problems of course. You can test the solenoids for opens and shorts with a multimeter by opening up the unit and testing across the windings.

 

[shags-72]

Do you know if there is a regulator from like napa or something available? I have seen a few 3 wire regulators but no idea how to rewire into that. Thanks!

 

[Ilikeurtractor]

I don't know of a Napa part #. There are other vehicles that used the same regulator but I don't remember specifics. I usually just try to fix the original mechanical ones. You can replace the solenoids in them with equivalents that are fairly cheap. I see eBay lists replacement solid state ones for Satoh if you're ok with the $77+ price tag which is somewhat ridiculous.

 

[shags-72]

Youch! $77! I will see what I can come up with and maybe open it up and look at it. Could dirty connections be the problem you think. If it is I don't know how to clean the connections inside the 4 and 6 place connectors. Thanks for your help sir!

 

[shags-72]

I just pulled the regulator and it is clean as a pin inside. Contacts don't look burnt at all comparing them to burnt points I have replaced before. But I can't really open them far to really see. What do you think?

 

[PILOON]

If you are real handy you could get a GM alternator that has single wire output with built in regulator.
Recycle yards often offer them for $25-35 range.0 and auto parts would have rebuilt as well.

 

[Ilikeurtractor]

Youch! $77! I will see what I can come up with and maybe open it up and look at it. Could dirty connections be the problem you think. If it is I don't know how to clean the connections inside the 4 and 6 place connectors. Thanks for your help sir!

Anything is possible when something isn't working correctly, although dirty connections isn't one I ran across yet as a problem. Loose yes, dirty no. One of the best things you can do is acquire the service manual for your machine and read up on the electrical system and how to test it in this case if you are seeking the cheap fix and would like to learn how it works. The manual steps through some troubleshooting techniques that should narrow it down. Or you can just pick up the eBay one. It depends on how much of a desire you have to dig into stuff and how much you value what you have to trade. Some people just want things fixed so they can move on. Generally that costs money. Some people would rather try to fix it themselves. Generally that costs time, either at the time of the repair or time spent on similar prior work. You probably have an idea where you fall in those categories.