john deere key sw

need key switch wiring diagram for John Deere 2010 tractor. Changed from generator to alternator. Wires were off key switch, need to know how to rewire. Thinking coil wire goes to I, B goes to battery, F goes to idiot light, S to starter. Not sure if right, please send correct diagram.

There are many different wiring diagrams for the 1010/2010 series. 12 volt, 24 volt, gas, and diesel. Also, many gas versions got upgraded key-switches that use an added wiring harness and ignition resistor.

Besides all that - makes a difference depending on what alternator you are using. If a Delcotron 10SI, 12SI or 18SI - is it being hooked one wire, two wire, or three wire?

Original gas engine key switch has L,B,I, F, and S. "L" goes to the generator idiot light, "B" goes to the L terminal of the voltage regulator, "I" goes to negative terminal of ignition coil, "F" goes to nothing, and "S" goes to the starter solenoid.

It's 12 volt, gas and now has a 12SI alternator done away with old voltage regulator built in alternator ran all new wires old one bad shape and change to neg ground, so with old voltage reg gone does B on switch go to battery now

The way you wire it depends on several things.

Is the 12SI using a self-excite regulator or a standard "three-wire" regulator?

Do you want to keep your "idiot" charge light?

Do you still have breaker-points in the distributor or has it been changed to Hall-Effect electronic like Petronix?

Do you have the original Deere key switch with the built-in ballast resistor or does it have a Deere upgrade with a separate ballast resistor mounted elsewhere?

IF you have a standard regulator in the 12SI - and you still have points - and you want the idiot light - this is how I'd two it.

The OEM key switch IF it has a resistor built into - won't work well for powering the 12SI field. If you have the Deere upgraded switch - the "I" terminal can be used. If you do that -you MUST put a diode in-line to stop the alternator from back-feeding and preventing you from shutting the engine off. Better yet -get rid of the Deere switch and buy a universal battery-ignition switch that has B, S, ACC, and IGN terminals. Hook the IGN to the wire that goes to your coil (or ballast resistor). I'd swap two primary wires around on the coil since you are using negative ground now. Use the ACC terminal to power the field in the alternator. This way, no diode is needed. The charge light gets wired in this line (ACC to 12SI fields which is #1 terminal).

The "L" terminal on your original key switch is what sends power to the headlight switch. So if you have headlights - you need to keep power to that wire, one way or the other.

The "B" terminal on the original key switch went to the "L" terminal on the old mechanical voltage regulator. Now that the regulator is gone - this needs to be wired directly to the battery positive and ought to be fused.

OK I have original type switch but it's new it's does have built in ballast I still have points and do want to keep idiot light, I have wire #1 on alt going to idiot light ( I was told if wired to light it wouldn't need diode in-line)#2 wire (12GA)&charge wire (8GA) running to hot post on starter, but you say OEM switch won't work well, why not?

OEM switch has a built in ballast resistor that comes off the I terminal. It is made for a fixed load that the ignition coil provides. When you put the extra load of the alternator field on it - its resistance will increase. It is made with the correct ohms resistance to power the coil only.

If you need to use the original switch - you can either tap into the power before the resistor for the alternator field - or just install a second switch for the alternator field. If you tap into the OEM switch then yes, you need a diode that can handle 5-10 amps. Otherwise once started, the tractor won't shut off.

Using a universal key switch with an ACC position makes it a lot easier. When "off" the "ACC" and "IGN" terminals are isolated from each other. If you use "ACC" for alternator field and "IGN" for ignition - no diode or extra switch is needed.

ok I'll get a universal switch hook it up that way thanks for the help