1864 Wiring Problem

[18647127]

I put a new DSAI ignition engine in my 1864 and can't make it run. It will run as long as the starter is engaged, but then stops shortly after the key is returned to the run position. Yes I have both wiring diagrams, but one is for the old engine and one for the new. Don't know how to meld them together. Any help would be appreciated.

[vince_o]

Steve

WELCOME

Sounds like you may have the wrong switch or the kill wire is hooked up wrong. I had the same problem, kill wire, with my command in a 482.

[J Hayes]

Steve

WELCOME

Sounds like you may have the wrong switch or the kill wire is hooked up wrong. I had the same problem, kill wire, with my command in a 482.

Welcome Steve!!
I need to ask Vince a similar question.... do you mean answering Steve's question that depending on the kill end if it be as my kt 17 has a coil that needs 12v power to run Vs my mag 18 that runs off the stator and needs ground to shut off.
I'm trying to figure how to do that myself when I go to do the change over. got a simple drawing??

[SWilliams]

Basically you have two types of switch on lawn tractors.
On engines with a magneto ignition system the switch will have a terminal marked M. This terminal has no connection except in the off position (where it gets shorted to ground)
On engines with battery powered ignition the switch looks the same but will have a terminal marked I. That terminal will have battery power in every position EXCEPT off.

Steve, you need to replace the switch with one for a battery ignition, not a magneto. The engine starts because when the switch is in start position it also sends power to the ignition. When you let the key back to run that power stops and the engine shuts down. It is a simple swap for the most part. Unplug one switch and plug in the correct one.

Jim, You just need the other switch as well. Then the wire that went to the M terminal on the old switch goes to the I terminal on the new switch. The other end of that wire would go to the pos terminal of the coil on the new engine.

[Tom Scott]

Jim, You just need the other switch as well. Then the wire that went to the M terminal on the old switch goes to the I terminal on the new switch. The other end of that wire would go to the pos terminal of the coil on the new engine.

Just want to add to what Steve said; may keep you from burning up a coil.

"The other end of that wire would go to the pos terminal of the coil on the new engine."...with the appropriate resistor for the coil in series. Most 12 volt coils are designed to have about 8-9 volts at the positive side while running. If you run them with full voltage (13.6 volts while running), the coil can burn up. Some starter solenoids (at least in the automotive world) have a stud that is meant to send the full 12 volts to the coil during starting only (bypassing the resistor during starting, hence you would have two wires going to the positive side in this case).

The extra wire from the starter solenoid is not necessary, but can be helpful if it is available.

[SWilliams]

Tom is correct. The resistor is built into the coil IF it's the correct Kohler part. All bets are off if it's an aftermarket "universal" coil.

[wdeturck]

When the auto industry(also tractors) went from 6 V. to 12 V. they all used an external resistors and kept making 6V coils and then coil manufacturers started to put the resistors inside which makes it a 12 V. coil. Car manufactures started to use the external resistors again when they found cars started better on 12 volts so they run a wire from the start position to the 6 V coll and use another wire through the resistor on the run position. I think if you had both coils you could detect which coil has a resistor(12 V) with an ohmmeter.

[18647127]

I found one cub cadet switch like you describe, 725-3021 from a cub 1912. This is a brand new Kohler CH740-3117 DSAI engine. Shouldn't it have the proper resistor built-in?

[mgonitzke]

18647127-

I'm still trying to figure out why several people in this thread are discussing battery-ignition coils when the engine in question has electronic ignition. All of this resistor vs no resistor talk has nothing to do with the original question That doesn't even apply to your tractor.

[Tom Scott]

Matt - As in the old days of this forum, sometimes the threads wander from the original path. Jim Hayes had a similar question, but with a traditional 12V coil type. Hence the discussion of traditional 12V coil ignition systems.

Steve Purdy (OP, 18647127) - You don't need any resistor with the DSAI installation. This was for Jim Hayes's discussion. I didn't address your original question because I thought Steve Williams had you covered, but I did a little research and it appears that in general the DSAI (Digital Spark Advance Ignition) needs three wires: Ground (black), 12V Positive (red), and Kill (white). I believe that Steve Williams was right in that the engine now only starts because you are presently only supplying the 12V Positive (red) during engine cranking. What has been missed is that you need a 12V Positive and a Kill wire (switched to ground) with this system. That being the case, here is what I think you need to do:

1) Keep your existing key switch (CC part # 725-3163), as you need the kill function. Connect the white wire of the DSAI to the existing magneto kill terminal, "M".

2) You need to supply 12V positive to the DSAI red wire during cranking and both run positions. This is accomplished as per the Cub Cadet 2182 wiring diagram that has a traditional 12V coil system. The way to accomplish this is to install a diode (CC part # 725-3208) between the "S" and "R" terminal of the key switch. A diode is an electrical "check valve" and only allows the electricity to flow in one direction. In this way you are energizing the DSAI in both crank and run positions, but not allowing the electricity to flow "backwards" during run and energize the starter solenoid. Connect the red wire of the DSAI to the "R" terminal of the key switch. **(On Edit: Make sure diode is installed to allow electricity to flow from the "S" towards the "R" terminal. "R"=Run, "S"=Start, "M"=Magneto Kill)**

3) Connect the black DSAI wire to a good ground.

Steve Williams was mostly right in that you need the same 12V supply as a traditional coil (non-magneto) system, but you still need the kill function. If you look at the 2182 wiring diagram you will see the diode placement. (Available on this site in the Documents & Manuals section.) The 2182 just doesn't use the "M" terminal because a kill wire is not needed with the traditional coil system.

[18647127]

Tom

Can't seem to find the 2182 illustration. I looked in the "documents & manuals" section. CC says that particular diode is not available.

[SWilliams]

Here you go

2182 main.pdf

(1.13 MiB) Downloaded 233 times

2182 indic.pdf

(956.82 KiB) Downloaded 224 times

2182 relay up.pdf

(1.83 MiB) Downloaded 232 times

For the diode you can use something like a 1N5402 , NTE577 or similar.

[Tom Scott]

Steve Williams - You're the man with the diagrams! I didn't know about the "relay upgrade", so this may help my 2182. Thanks!

Steve Purdy - Don't get too wrapped up in the 2182 wiring diagram; it is only to illustrate the method Cub used to provide a 12V positive to the ignition in Start and Run modes. The only part of the diagram that applies to your situation is the jumper with the diode from the "S" to the "R" terminal. I suggested the Cub part number as it showed still available on the parts site I use and it didn't require researching a diode. Steve Williams is right, any common diode that will handle the amperage will work. I don't know how many amps the DSAI draws, but it is probably pretty low. The worst that could happen is that you burn up a diode and get a larger one. You could measure the amp draw of the DSAI with a multimeter; I would bet it is easily less than 3 amps.

The diodes that Steve Williams suggested are both available at Radio Shack for almost nothing. There are probably twenty different commonly available diodes that would work.

[Tom Scott]

OK, Steve Williams got me to researching diodes. All things have engineering trade-offs, so...

I am getting pretty picky here, but if you are going to spend the same 5 bucks on a diode, you might as well get one that is optimal. All diodes create a voltage drop in the forward direction (direction you want electricity to move). Both of the diodes Steve Williams suggested would work, but the first one is only good for 3 Amps. I am just not sure what your ignition system draws, so I want to err on the side of a little more amperage. The second one suggested has a high voltage drop, 1.7 volts, which could cause performance issues.

After reading too many pages of diode specs, I think you would be best off with a "Schottky Barrier" type diode (which is the NTE type suggested). Schottky types have a lower voltage drop. The one suggested has a higher voltage drop because it is good for 1000 Volts. You don't need 1000 Volts, you only need reasonably greater than 12 Volts.

I suggest you buy an "NTE573". Similar item, but rated at 60 Volts and 5 amps, which should be plenty; the engineering trade-off is that now you only have a 0.7 Volt drop across the diode. That voltage drop is at rated amperage, so it will probably be less at low amperage. Data Sheet: http://www.nteinc.com/specs/500to599/pdf/nte573.pdf

Available online only at Radio Shack, and many other online places: http://www.radioshack.com/product/index ... Rectifiers

Heat is the death of diodes, so clamp a pair of vice grips (as a heat sink) to the lead between the diode body and your terminal end before soldering a connector on, or use some type of mechanical connection (screw terminal, crimp connector, etc.). Always use dielectric grease on all mechanical electrical connections.