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Scag Turf Tiger Electrical Issues

Discussion in 'Mechanic and Repair' started by myedsore, Apr 22, 2015.

  1. myedsore

    myedsore LawnSite Member
    Messages: 6

    Hi guys I have recently taken ownership of a 2001 Scag Turf Tiger that was badly maintained and plan on rebuilding over the winter. I am based in Australia so parts are scarce and Ebay and US seem my best best.

    It was not running (25hp Kohler VTwin) when I bought it but that turned out to be two blown head gaskets, a bent pushrod and burnt exhaust valve. $400 later and the engine is running a treat.

    The previous owner decided to change the wiring so I am trying to figure out the correct wiring to put it back to standard. I have both the Scag & Kohler engine diagrams however I am struggling at the Kohler plug as it seems I do not have correct wires.

    The key switch on the Kohler engine has to be turned to 'ON' and then start the engine from the Scag control panel. However to turn off the engine I have to turn the Kohler key switch 'OFF'. Turning off the Scag control panel does nothing.

    My wiring loom from the Scag control panel where it connects to the Kohler plug contains three wires. A yellow wire (fused in the control panel), a white wire and a green/white wire. When I got this machine the yellow wire was connected to the yellow wire on the Kohler keyswitch which I believe is the 'ACC' and this blows fuses if left connected. The white wire is not connected to anything on the engine and the green/white is connected to the starter.

    Also I have no reading on the Ammeter but I have tested the meter and it does works. i also have a charging voltage of 13.8 volts on the violet wire which is connected to the starter terminal that connects back to the battery.

    Would someone please be able to tell me the correct wiring from this plug to the Kohler engine as I do not think this is right and I should be able to start and turn off at the control panel.

    Oh yes this is a fixed timing engine just has two coils not special ignition modules.

    I have attached some photos of the wiring.

    Hopefully this helps.


    Mark from Oz.



  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,001


    I'm unsure on the ammeter, but if you notice the white wires connected to the ignition coils, these are the kill wires. The white kill wire should be hooked to the "M" (mag) post on the ignition switch, if the switch is good and has a good ground the engine will shut down with the key......
  3. OP

    myedsore LawnSite Member
    Messages: 6

    It does switch off but there are two key switches. Not sure if this is standard for Scag mowers but think engine was replaced so maybe that's why it has two. The one on the engine itself works fine but the Scag does not.
    Posted via Mobile Device
  4. BigFish

    BigFish LawnSite Fanatic
    Messages: 5,589

    You need to download a wiring diagram from the Scag website. http://www.scag.com/OPManuals/STT/STTOPMANTOC.html
    Match it up to the engine diagram in your Kohler manual and bingo.
    It shouldn't be too hard to figure out.
    Print out a couple copies and use colored pens for each circuit. ( some diagrams are already in color)

    Obviously ya need to get rid of the extra keyswitch.
    Last edited: Apr 22, 2015
  5. OP

    myedsore LawnSite Member
    Messages: 6

    Yes I already have the wiring diagrams. It isn't that simple. One of my biggest unknowns is what the yellow wire which is connected to an extra tab on the Scag keyswitch connects to on the engine side.

    If I know this I can figure the rest.
    Posted via Mobile Device
  6. BigFish

    BigFish LawnSite Fanatic
    Messages: 5,589

    It's fused, right, so it could be the charging wire. I mean, c'mon, trace the wires out that ya got staring you in the face. Is it hot in on...start...acc... off ???
    Figure out the rest of the engine's wires and it should be apparent.

    With no ser. numbers or eng. numbers, I'm done.

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