Check that the ignition 'STOP' wire isn't chafing/shorted on anything. If that checks out, get the multimeter out and check that there is an open circuit between the disconnected 'STOP' wire (loom side, not engine side), and chassis ground. Whist checking this, you need to be IN THE SEAT, ignition ON, blades OFF, brake ON. If you read a short, or very low resistance, you have either a faulty interlock switch (likely), or a chafed/shorted loom. You don't say what model, but if you have the electronic dash, it's possible (but unlikely) you have a faulty PCB). A blown fuse in the supply to the PCB will also do this, but then you will have no display. Also, the electronic version needs a GOOD battery. A dead cell can cause a no-start - even if there is enough to actually crank the engine.
phil_saunders(a)bigfoot.com
Phil Saunders, May 2012
