Electrical flow diagram for MT

Wanted to know if someone could please point me in the right direction to access the information that enables someone to understand the electrical flow for my MT. Basically I wanted to understand the relationship between the key electrical components: [ign. switch, ammeter, cut-out-relay, battery, starter, generator, coil and distributor/points/condenser/points and plugs] and the flow of the voltage--how, why, etc...This will enable me to more accurately troubleshoot my problems and answer questions more effectively...it will also reduce the # of my repetitive posts. Thanks to you guys, I have the "M" wiring diagram and know all of the components.

Thanks for all your help and God Bless our troops and their coalition forces.

tom

~Lets start at the battery� the positive post of the battery is grounded to the tractor chassis, the negative post is hooked to the starter switch on top of the starter. As far as cranking the engine, that's all there is to it. You just pull the starter rod button & the starter drive engages the flywheel & the switch contact hooks the battery power directly to the starter windings.

~Now for the charging system� The generator is grounded to the chassis so that is a given.. There are 2 parts to the charging system, the first part is the ARMATURE side, when the armature spins inside a set of magnets it produces power, the faster it spins or the greater the strength in the magnets the more power the armature produces. The armature is hooked to the battery first through the cut-out relay [all that is for is to connect the armature to the battery when it is charging & disconnects it when the charging voltage is below the base battery voltage],,then to the ammeter [all the ammeter does is allow you to see how much current is flowing to or from the battery],,, then to the starter battery cable stud [all that is, is a path for the charging current to get back to the battery�The second part of the charging system is the field [magnet] strength control, [remember the stronger that the field magnet is the more the generator charges],,, the field winding in the generator is powered on one end from a movable 3rd brush that picks up it�s power from the armature [the closer the 3rd brush is to the armature power brush the more power the field CAN receive. The other end of the field winding is hooked to the headlight switch, with the headlight switch in the [OFF] position the low side of the field winding is hooked to ground through a 2-3 ohm resistor on the light switch so the field only runs at partial strength. When the headlight switch is turned on so the lights operate, the generator must produce more power to keep up with the lights so that fields wire is then completely grounded at the light switch & the field is then at full strength [or at least as high it as it can be by the position of the 3rd brush]. That pretty well covers the charging system� The cut-out relay is just a set of contacts that are pulled together by an electro magnet. The ammeter is just a gage that measures current flow & is calibrated to move a pointer a certain amount for a certain current flow.

~Now we have the ignition system�basically all that has is an off/on [ignition] switch that gets it�s power from the non-battery side of the ammeter, the power from the ammeter to the ign switch goes through a dash mounted fuse before reaching the ign switch for circuit protection. From the ign switch the power flows to the ignition coil�s primary side winding & then through that winding to the points inside the distributor. With the points closed there is power flowing all the way from the battery through the ammeter, through the fuse, through the ign switch through the coil�s primary winding then through the points to ground. When the points open the power in the coil�s primary winding abruptly stops & that induces a current flow into the coil�s secondary windings. The primary winding in the coil has fewer turns & is a little heavier wire than the secondary winding in the coil. Both the primary & secondary windings are wound around the same common iron coil core, so when the lower voltage primary winding abruptly stops passing current & the magnetic field inside the coil collapses that induces a current flow in the secondary windings that is a much higher voltage [can be as high as 10-15, 000 volts] & that is the voltage that jumps the plug gap. When that high secondary voltage is produce it not only tries to jump the spark plug gap but also tries to jump the points gap as they are just starting to open. To keep the points from burning a condenser is placed in between the points coil side contact & ground, all that condenser does is give the secondary high voltage a place to go [& get stored] until the points open far enough so a spark can�t jump across them. The only thing left is to have all that secondary voltage get to the proper spark plug at the correct time as the piston is just before TDC on the compression stroke & that is what the distributor cap & rotor does. When the piston that is about to fire is just before TDC the distributor lines the rotor up with the correct plug wire for that cylinder, then opens the points at just the correct moment to produce a spark to that wire�

~This is just a quick how-it-works on the Deere �M�, any questions or further explanations just post back with questions�..

God Bless the USA and protect our brave young troops. Ol John T Nordhoff in Indiana

Thanks Ol John T...I would be interested in you e-mailing anything that would help a novice to more effectively teach himself how to troubleshoot, isolate and understand the electrical flow when: (1) what happens when the ign switch is turned on but not yet cranked
(2) what happens during the cranking process
(3) what happens when the tractor is operating
(4) what goes on with each component and their inter-relationships during (1-3)...

If there is a book [based on 2 cyl jd's or similiar] I need to buy, just point me in the right direction ! Thanks again, tom

God Bless the Troops !

1. When the ignition switch is turned on, current from the battery flows through the ammeter, to and through the closed ignition switch contacts, to and through the coils low voltage primary winding (lil + and - terminals), to the distributor, and then to ground via the ignition points when they are closed. When the distributors cam opens the ignition points breakign that circuit, high voltage across the coils secondary winding causes current to flow to the plugs, arc jump the plug gap, and ignite the fuel at TDC on that pistons compression power stroke.

2. Durign the cranking process, when you engage the starter pedal switch, current flows from the battery, through the start switch, through the start motor cranking the engine.

3. When the generator turns and its output voltage becomes higher than the battery voltage, its cut out relay contacts close allowing current from it to enter the battery via the ammeter charging it. When the tractor is shut off and the generator voltage is less than battery voltage, the cut out relay contacts open so the battery doesnt get discharged through the generator.

The light switch just closes permittign battery voltage and current to become connected to the lights powering them, again first through the ammeter from the battery.

The light switch also has a resistor circuit (field current controlled generator output regulation) which dead grounds the generators field winding allowing max gen output when the lights are on, but a resistance in the field circuit to ground causing a lower generator output when the lights are off.

Like my first post said, theres a real good JD published book on basic tractor electricity, and I will gather up and e mail you my past electrical articles published in Green Magazine, but they are fairly long winded and complex but may help.

Good Luck, God Bless the Troops and the USA

Ol John T Nordhoff in Indiana