Command 18 swap into a 782 (wiring)

[jgibson]

I am in the process of putting a Command 18 into a 782 and am looking for some help w/the wiring. I previously had this motor in a 682, but I had someone else do it and the tractor never charged. The wiring harness was so hacked up it didn't make any sense. I have wiring diagrams but to be honest the more I look at them the more confused I get. Electrical stuff is not my strong suit. I am looking for any help I can get, any suggestions or comments would be greatly appreciated. Thanks in advance.
Jerry

 

[jchamberlin]

Jerry, although I feel your pain, you need to be more specific than "Help!" First off, what is the serial number on your 782, the wiring scheme changed at 720,000. Second, what does the Command 18 require? That is, what sort of ignition and charging systems does it use? Does it use a coil or does it have a magneto? Is the output from the stator AC or DC? does it have one wire or two? Is there a rectifier installed on the motor? Basically: what connections are available at the motor?

Finally, what are you finding on the 782 chassis? You should be able to compare the wiring you find on your tractor to the wiring diagrams for the appropriate version of the 782.

I can tell you this: the 782 SN < 720,000 had two connections to the motor: one for the DC output of the regulator/rectifier at the engine that went directly to the key on a 10 AWG wire and one for the ignition coil that connected to (1) the seat switch and (2) the PTO switch at terminal 4. Both of the 16 AWG wires at this connector eventually wind up at the key also, but I need to know more about the ignition switch you have installed in your tractor to identify the terminal.

I know it can get very confusing, especially when you don't know what you're working with. I've learned all I know about tractor wiring from starting in much the same position as you are now.

For starters, lets identify which 782 we're dealing with. Check out the diagrams below and tell me which one applies to your tractor.

 

[jgibson]

Sorry I wasn't more specific. The 782 is Pre 720,000. When I first had this done in the 682, Ken U was about the only one at the time that I knew of had done it(long time ago). I was told that I had to update the key switch to one out of an 1864. The old notes I took down were, It is a magneto motor, dont need the solonoid. Not very good notes, live and learn. The Command motor has 3 wires on the left side, 2 white that come from the stator goes to voltage regulator and 1 that looks violet. On the right side it has 5 wires, as far as I can tell, 1 green, 1white, 1 looks purple, 2 red. Didn't find a second color on either red. I have schematics for pre 720,000, an 1864, and manual for a Command 18. Trying to combine all of them is making me crazy. I like your diagrams a lot better! Thanks again!

 

[jchamberlin]

Jerry, I know what you mean about the notes, it all seems clear when you put down the first time, but when you pick it up months later, its like, "What was I thinking?"

Lets start with the easier stuff. You say there is a voltage regulator on the motor fed by a 2-wire stator; this is good, it means your stator's output is AC and the regulator is rectifying it to DC. The DC output of the regulator goes directly to the key.

As far as the key goes, can you identify the terminals and the key operation. This is important information. It is worth lifting the gas tank half-way out. Take a picture of the back of the key with the wires still connected, or at least note their color, quantity, and location. I like to orient the key as shown in the diagram with the odd terminal to the right, and number them starting from the top left ending at the odd terminal at the side.

Next, verify the key's operation by using an Ohm Meter and checking to see which terminal connects to which at each position, including the OFF position. Meanwhile, I'll check to see which key came in the 1864. I'll post the key info for the part number often supplied for the tractors with magnetos-- 925-3026. The only change I would make in the graphic, is that I think the "R" should stand for "Rectifier." It is the terminal to which the Regulator's output should be connected. Without the regulator connected to the battery, the battery never get charged when the engine is just running.

I'm curious to know what the other bunch of wires connect to on the motor. Do some of them run to an oil level sensor, or is there a relay mounted somewhere on the engine?

 

[jchamberlin]

Jerry, according to Parts Lookup, both listings for the 1864 used the 725-3163 key. I happen to have a 925-3163 key, but never used it in my 782 conversion, I couldn't figure out how to wire it. Now that I'm all through with my modifications (using an interposing relay), I can see a way it could be done with the -3163 key without a relay. The only functionality one loses is the seat switch interlock; I think you also allow the user to start the mower with the PTO engaged. If you're OK with removing those safety circuits, the wiring at the key could be modified to allow the use of a magneto-style key in a coil-type chassis. Other forum members who have performed the same mod are welcome to critique, but I'm having a really hard time understanding how a "passive off" system can be converted to "active off" without using a relay at some point to convert the signal from positive coil voltage to a "kill" signal at ground potential.

Anyway, I dreamed up the following scheme that I think would work. Please note that some of the existing wires must be re-routed and others should be disconnected to keep stray voltages out of the system.

Final thought: You might want to put a diode between the Rectifier and the Ammeter to keep the battery from possibly discharging through the stator, although it may not be a problem. Power diodes are available at Radio Shack.

 

[jgibson]

I'm going to be gone over the weekend but will look closer at it once I get back. This is what I can tell you about the schematic in the command manual.
--2 red wires come from fuel shut off solenoid and one goes to R on key switch, one goes to S.
--1 white wire goes to M.
--1 violet goes to R.
--1 green goes to ground.
That is the only violet wire so I assume that the one on the left side of the motor goes to the B+ on the VR and the one on the right side it hooks up to the switch. It also shows a blue wire that is run from the S on the switch to the starter.
It also shows an optional oil sentry shutdown switch, which shows a ground wire and a green wire that hooks in with the white wire and goes to M. I thought my motor had the oil shutdown, I have to look but if it does shouldn't I have 2 green wires? One for the ground and one for the shutdown? I really appreciate all the help. I will try to get this scanned so I can post it. Thanks again!

 

[jchamberlin]

Jerry: Have a good weekend. I'm going to enjoy having my kids (and grand-kids) here at my place. I'll check in next week. We'll get you going again.

 

[jgibson]

Well I finally had a chance to do some work on this again. I hooked up a bunch of wires that I thought were right, went to hook the neg up on the battery and got a spark show. Obviously I have something terribly wrong! I hate wiring!

 

[ibyers]

Jerry,

Here is how I wired mine.

Good luck,

Ike

 

[jdeshazo]

Would this wiring be the same for a mag 18 going into a 782

 

[jchamberlin]

Josh: Roland Bedell drew up a diagram for an M18 swap into an early 782, changes were made to the wiring for the later 782 models (S/N 720,000 and higher). I'm not sure if Roland's colorized schematic is available in the Manuals section of this forum or not.

Please note that not all M18 engines included the oil sentry circuit.

 

[jdeshazo]

Thanks now I'm just wondering about the relay shown I don't remember seeing one on my 782 is that an added relay for the mag 18

 

[jchamberlin]

Josh: Yes. The relay is added so that a ground can be provided to the "kill contact" at the magneto when the key is turned off. In other words, the 12 volts originally provided to the positive side of the coil in a 782 with a KT17 engine, is provided to a 2-pole relay instead in a 782 equipped with a Mag 18 or any other engine with a magneto-fired ignition system. The Normally Closed (NC) contact of the relay is wired to the "Kill Wire" of the magneto, and the Common contact is connected to ground (or visa-versa).

This way, when the key is in the "Run" position, the "Run with Lights" position, or the "Start" position, the relay is energized and there is no connection from ground to kill wire; but when the key is on the "Off" position, the relay de-energizes, and the magneto is grounded out, killing the motor.

Note: The challenge for an ignition with a coil is getting the engine started; the challenge for an ignition with a magneto is getting the engine stopped --be prepared!

 

[jdiederichs]

Josh,
The relay is added for this engine swap. You can use the CC # 725-1375 relay or one from any auto parts store that has the terminals (5) numbered 30, 85, 86, 87 and 87A rated at 10 amps or greater.

 

[vtreece]

I have a Kohler magnum m18 in a CCC red 782 sn above the 720000 stator may be bad on the engine.. Iwondering where to connect the magneto kill wire coming from the engine..??? engine has 1 black wire.. kill and 1 red wire charge. key switch is 925-3021. engine starts and tractor drive but I'm looking for the correct way to wire the kill... also where should the red charge wire be connected...at key switch or all the way back to solenoid/battery... please help..desperate... [email protected]