The charging system on my Mf65 diesel is a mess

DaleM

New User
The charging system on my Mf65 diesel is a mess, but I don't think I have to deal with that right away, because I won't be using much current and the tractor came with a large deep cycle battery in it. The generator is not the correct one and didn't pass a voltage regulator bypass test. The voltage regulator has serious internal corrosion.

I'd like to correct other electrical issues, though while I have the control console apart and am becoming familiar with the system (I'm not great at this stuff, but at least this looks relatively simple.) A lot of the wiring has been replaced with black insulated and, otherwise, original colors have faded, so the color codes aren't a great help.

Compared to the schematic, there appeared to be oddities in the wiring. I believe I have restored connections to the schematic specs. The odd connections appear to be misguided efforts to remedy problems in other parts of the system.

For example, in the schematic, the keyed switch appears to be connected to battery voltage at terminal 3 through a 10 ga wire connected to the voltage regulator at terminal L. However, presently there is never battery voltage at terminal L, only at terminal B. So, short of restoring the charging system to power up the rest of the system, I wondered if it would be alright to temporarily pair the keyed switch supply wire from terminal L to terminal B on the voltage regulator with the 10 ga ammeter wire.

But, another thing about the keyed switch is it doesn't seem to be functioning correctly. I tested the switch contacts for continuity in various switch positions and the results follow:

The keyed switch appears to be single throw, momentary contact when turned in either CW or CCW direction.

*In the CW direction there is continuity among all the terminals

*In the neutral position there is continuity between terminals 3 & 4 only.

*In the CCW, position nothing is connected. I cant see a point in a momentary disconnect position.

And the manifold heater and starter solenoid are connecting in the at rest neutral position which seems odd to me. But, as I said, I'm not great at this. Can anyone make sense of this and help me understand what I'm looking at?
Dale
 
I was looking at the schematic last night. Can not understand what the reason for powering the start/preheat switch through the regulator...

There must have been a reason, but for now, I would do just what you are asking, power it from the B terminal, see what happens.

Looking at the switch diagram:

Neutral position should be open. No connection between any terminals.

Turning CW would connect 3 to 2, energize only the starter.

Turning part way CCW will connect 3 to 4, energize preheat. Turning it further will energize 3, 1, 4, preheat and starter.

I agree, the switch is defective if it is connecting any terminals at rest.

Just something I observed, the wiring diagram has NO overload protection! You can buy a fuse link at the auto supply. Be a simple solution to add a fuse link to the wire from the battery side of the solenoid that feeds the amp meter.

Long term charging solution, convert it to a one wire Delco alternator. Good luck finding a reliable regulator. If the tach drives off the generator, you can get an alternator with a tach drive.
 
There is an oil pressure switch that turns on the fuel gauge. If you use a two wire alternator you can turn it on there. A better design then the early JD 3020/4020 where the key turned on the fuel gauge, you could shut off the tractor with the diesel stop and leave the key on.
 

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