Shop Products
Houzz Logo Print
trado11

Wiring question

trado
9 years ago

I posted earlier but can not see it so I apologize if it double posts.

Anyway I had a wiring question on a Mower I am working on. I am replacing a Kohler Command with a Briggs twin. The Kohler had two wires with the one going to the coil and the other going to the alternator whereas the Briggs has the black to the couil and then a red/white and grey going to the alternator. How do I wire this up to work. Thanks

Comments (10)

  • mownie
    9 years ago

    ***" red/white and grey going to the alternator."***
    Does that mean a Red wire with a white stripe?
    Or, a Red wire and a White wire" ?
    Or, a Red wire in a white connector?
    If you can post a photo it might help because I have looked through all the Briggs manuals I have and I don't see any of those combinations, and none that also feature a Gray wire.
    What is the model number and type number of the Briggs engine you are using?

  • trado
    Original Author
    9 years ago

    The wires going to the plug are the colors here are the motor wires

  • mownie
    9 years ago

    OK, that configuration is the 3 amp DC, non regulated charging system.
    On this system, the maximum DC output will be around 3 amps at governed engine RPM, lower RPM means lower amp output.
    The red wire is the DC lead and must be connected to the battery positive circuit. Usually this wire will lead off to the battery positive cable on the starter solenoid or the key switch.
    The black lead is AC output and can only be used for headlight operation. Here again, this is non regulated AC and if used for headlights, the lights will be dim at low RPM and brighten as RPM increases.
    The only way I could tell you what the wires on the chassis side of the project connect to on the engine side would be if I knew the model of the tractor and had a wiring diagram of the tractor.
    I still can't read the model and type numbers on the engine in the photo.
    I hope your tractor has a manually engaged deck drive belt.
    If your tractor has an electric PTO clutch, you don't have enough alternator output to run the electric PTO and charge the battery too.

  • trado
    Original Author
    9 years ago

    Thanks for the info mownie The tractor model was a simplicity 5216 and the engine is a briggs 402707. It is being put on a scag stg-18kh. It is manually operated deck so no issue there. So you are saying the headlights were AC?

  • mownie
    9 years ago

    ***"So you are saying the headlights were AC?"***
    There is a great possibility that they were powered by AC.
    The same incandescent light bulb can operate on AC as well as it does on DC ( and vice versa, remember incandescent light bulbs in homes before the CFL flood?).
    The 3 amp, non regulated alternator is a complete "compromise" type of charging system aimed at providing a minimalist solution for minimal conditions for minimal cost (to Briggs).
    They are counting on the budget system to be adequate to recharge a typical mower battery in the average mowing time under average conditions.
    Hence, only a simple rectifying diode to convert one leg of the stator coil (alternator) to DC for charging the battery, instead of a full voltage regulator.
    The AC scheme for powering headlights is based on the fact that the stator coil output is AC. Because AC CANNOT be used to charge a battery, the diode essentially "chops off" one phase of the AC to create a pulsed DC to charge the battery. The Black wire in the stator lead is the "other end" of the stator coil windings, which is non regulated, non rectified AC. Same single stator coil but 2 very different current outputs.
    Many, and I mean many.......tractors are built having AC powered headlights.
    What are the wire colors on the Scag where the Scag chassis harness connected to the Kohler engine harness? A photo of the Scag connector might also be helpful.
    I have just one Scag wiring diagram here and it is for a Kohler engine powered SSZ.
    The manual I have does show the SSZ to have an electric PTO and the Kohler specs list it as be a 15 amp alternator.
    But if your Scag has a manually engaged cutting system, that part of the equation does not apply. And the SSZ is not shown as having headlights, but even if it had them, they would likely not be powered by AC (with a 15 amp alternator, plenty of juice for DC lights).
    If your Scag does have lights, and you use them, you will need to utilize the AC leg for that.
    I will thrash around and see if I can come up with a diagram of your STG-18KH.

  • mownie
    9 years ago

    OK, Red wire in stator harness connects to the Yellow wire in the Scag chassis. Note, the Scag Yellow wire runs to the NEGATIVE side of the ammeter.
    The Black wire in the Briggs stator harness needs to be taped off if you must separate the Red and Black wires out of the Briggs harness connector to make your splice to the Scag harness. Unless of course you have some lights to run.
    The Black wire from the Briggs MAGNETO will connect exactly like the Kohler magneto wire did.
    DO NOT get the Black stator wire crossed up with the black magneto wire. If you do, kiss the mag goodbye.
    On the image I posted, I meant to rename the Red wire as "red" but I got too fast and missed that point. Just consider where I painted the Red wire leading from the Briggs alternator as "should say Red" in the image.

  • trado
    Original Author
    9 years ago

    Thanks mownie you have given me way more info than I could have imagined. Big help and I appreciate it.

  • trado
    Original Author
    9 years ago

    The wiring went perfect on this and the motor runs perfect, Except-----I am not sure I have the throttle on the correct linkage. Can someone assist me on this? Thanks

  • mownie
    9 years ago

    See images. The photo is of my 422707, but it should be the same as the 402, provided your engine has the metal intake manifold. If your engine has the plastic manifold, my condolences.
    The throttle cable coming from the control console mounts onto the intake manifold with a clamp and a single machine screw.
    The cable lies in the groove and the screw clamp secures it.
    Throttle cable travel is adjusted by moving the cable in the groove.
    Hope this helps.

  • trado
    Original Author
    9 years ago

    Mower is running like a champ. Thanks for the help.

Sponsored
Ed Ball Landscape Architecture
Average rating: 4.8 out of 5 stars30 Reviews
Exquisite Landscape Architecture & Design - “Best of Houzz" Winner