Scag Walk Behind Dies when Transmission or Blade Engage

Discussion in 'Mechanic and Repair' started by bapster, Jul 6, 2011.

  1. bapster

    bapster LawnSite Member
    Messages: 1

    I have a 2008 Scag 36" walk behind (belt driven) with probably 50 hours on it. I've had a few problems in the past with the engine dying when I place the transmission into gear. Some fiddling with the Operator Presence Switch and it seemed to be OK. The other day I just started mowing and after 30' or so it dies. This has never happened before.

    I was able to get it started but now if I engage tranny or blades it dies. If I remove the tranny switch then engaging tranny is fine. I tried jumping the Operator Presence Switch and it still dies engaging either. The blades or blade drive mechanism is not jammed as they turn easily. It definitely seems like an electrical kill and not a mechanical kill.

    It's possible the tranny engage and blade engage are entirely separate issues and both have become issues at the same time. I did some voltage checking at one point and was surprised to find a varying voltage between 20 and 28 volts on one of the wires on the blade engage harness.

  2. scagwildcat

    scagwildcat LawnSite Senior Member
    from nw. ct.
    Messages: 507

    it could be several things, i would start with the safety switches, if they are good, its most likely the rectifier or the voltage regulator. depending if you have electric start or not...
  3. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    For reference, I am assuming the switch you speak of is a plunger style.
    And if it is Scag's Plunger-style operator presence safety switch is normal OPEN.
    Meaning that you depress the plunger to CLOSE the connection (allowing current to go through).

    For example...
    If you were to use Scag's plunger switch to light up a light bulb, you'd have to PUSH it to get the bulb to light.

    Released it's off.
    And the switch's normal position is released (or off).

    What you have to find out is whether the switch needs to be ON (or OFF) for the machine to function as you wish.
    If it needs to be ON, then you can temporarily unhook BOTH wires and tape them together.
    If it needs to be OFF, then you can temporarily unhook ONE wire.
    If either of that fixes the problem, your switch is likely bad.

    This one:
    (btw Napa sells them)

  4. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Might be a safety module going bad.
  5. js12121212

    js12121212 LawnSite Member
    Messages: 1

    Try replacing the fuses. If that doesnt work try a new battery and/ or trying to clean up the battery connections.

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