Very weird lawn tractor electrical problem

[iwctygr]

I own a Murray lawn tractor. Have had it for about 9 years. It is garage kept. In pretty good condition. I do all the routine maintenance. Change oil, blades, filters etc... have replaced the battery twice and soliniod once. No other problems. Today after mowing the back yard I parked it in the garage and shut it off to go get a drink of water. The key was out and the engine was off. I heard a loud electrical buzzing like a overhead powerline but much worse. Sounded like a real loud buzzing. I stuck the key back in and tried to start the engine, no go. Got off the tractor to see if the dead man switch in the seat would cut it off. No go. I was getting worried like it would blow up, so I pushed it out of the garage and disconnected the battery. Buzzing stopped. Pushed it back in the garage. About 2 hours later I reattached the battery. Positive (red) cable

1st. Negative (black) cable second. When I touch the black cable to the battery terminal the enginge tries to crank over. All I would need to do is give it gas (choke) and it would probably start. Heres whats weird. THE KEY IS IN MY POCKET (IGNITION SET TO OFF), THE BRAKE/CLUTCH IS NOT PUSHED IN (HAS TO BE TO START) AND THE DEADMAN SEAT SWITCH IS NOT PRESSED IN BECAUSE I AM NOT IN THE SEAT! It should not be trying to start. There are 3 thing that should keep it silent, but every time I touch the black battery cable to the battery it tries to start up. Is this a short of some kind? What do I do? My grass is almost shin high and I have a good sized yard. Any help would be greatly appreciated.

[MLD]

You need to look at the electrical schematic that came with the tractor. Obviously it's not gremlins--you have a short from the battery to the starter to ground which is by-passing the ignition switch and all the various disconnects and safety switches. Get hold of a multimeter that will let you check resistance (ohms). Disconnect the battery leads and walk you way through the system (using the schematic as a guide) and see if you can find the short to ground. You're looking for a short that is upstream of any normally functioning component or switch that should prevent this from happening. I suspect it will be very close to the starter. MLD

[Chris Lewis]

According to MLD :

If the Murray has a starter solenoid/relay like a car (may be part of the starter) it _may_ have fused/jammed itself with the contacts closed. Loud buzzing is suggestive of a solenoid/relay problem. But it may just be a symptom of a short elsewhere.

[iwctygr]

quoted text -

Replaced the solenoid under the suggestion of a repairman who was too booked up to make it out to take a look. It worked. The older solenoid had locked up in a position whick bypassed all the safety switches I guess. You were right on the money Chris. Thanks for all your help guys. PS. In the process of fixing one problem (the tractor) I noticed another. I have a quarter sized dark spot in the garage sheet rock ceiling. I touched a screw driver to it and it went through. I reemed the hole out with my thumb and thats as big as it got. I tried to look up inside with a small flashlight and saw AC ductwork and the hoses from the outside AC unit do come in that way. I figure condensation at best. I put a bucket underneath and the drip is about 1 per minute or less. Just goes to show you, it never ends.

[Steve Barker]

sounds like your starter solenoid is stuck or the spring in it broke.