Howdy,
I have a Husqvarna cz3815 zero-turn mower with a 15 hp ohv briggs & stratton engine. While cutting the lawn, it stalled, then after a few minutes, it started again. This happened a few more times, now it will not even turn over or even click. I have checked the starter and ignition fuses, changed the fuel filter, changed the spark plug and disconnected all the connections and sprayed them with electronic contact cleaner. Now the lights will come on in the first position and the mower will start if I jump across the large positive terminals that run between the battery and the starter. It will continue to run. I feel I've missed something, most likely very small, but I'm stumped for the moment. Any suggestions would be helpful.
Thanks,
Kupgas

Maybe a long shot but I suspect your ignition switch has failed. If you have test leads try to check for continuity across the ignition terminal when the key is turned. Do this with the battery disconnected. Connect the battery and chcek to see that 12 vdc comes into the ignition, turn the key and it should pass through the switch to the starter.

Thanks for the answer. I used a voltmeter and went searching. I'm getting 12 volts out of the ignition switch, but not to the solenoid. I've checked the relays(all three are the same part number) and even switched them around. I checked the solenoid by taking it out of the mower, applying 12 volts to the control terminal and it clicked and closed the switch, but when I reinstalled it, I'm not getting even a click, even with a boost with cables. I purchased a solenoid from a tractor supply house here in Jackson, but it didn't work either. I'm guessing since the new solenoid has two control terminals, it might be insulated from the frame and have to be grounded separately. I'm thinking one of the relays is bad, because it looks like the schematic shows EVERYTHING hooked up to the starter relay, so if something goes out, the machine will not get power to the starter. Happy Easter

A failed ignition switch is a logical sudgestion given the info at hand, I have only seen MAYBE 2 over the last 25 years repairing and as a service manager. The battery connections and cables are subject to the elements and low voltage because of starting and stopping. This makes for common failure such as batterys, solenoids and starters burning up.

I have put together a series of tests that should solve the problem without a doubt.

You will need a volt meter and set it to DC volts
-Check the battery for 12.5 Volts
-Check the cables attached to the battery for the same voltage checking for good connections
-Attach the positive side of the volt meter to the + side of the battery and the negative side to the engine block, Still got 12 Volts? If not the ground from battery is bad.

-Now keep the ground on the negative side of battery
-follow positive cable to the solenoid and hook volt meter on the cable going TO the starter coming from the opposite side of the solenoid.
Turn key to "start" position you should have 12 + volts

YES-Check the same way on the starter motor where the cable FROM solenoid connects, If less or no voltage then cables or connections bad, If good voltage then starter is bad

NO- Take positive lead from volt meter to small wire going to solenoid and test for 12 Volts with key in the "start" position, If no voltage to small wire safety switch is telling it not to crank or ignition switch is bad (rare) If it does have voltage the solenoid needs replacing (common)

Hope it helps,
.Don

Don,
I appreciate all the help given on this site. Thanks for your suggestions. Can tell you I definitely have 12 volts at the battery, and I do not have 12 volts coming from the small wire to the solenoid when activating the starter position of the ignition switch. I will check the ground and double check that. I have a feeling there is a safety switch that's fubar or there's a problem with the relay system.
Thanks,
Kupgas

SNAFU, no 12 vdc to the solenoid sounds like bad ignition or safety switch. You can check you safety switches with a continuity tester. You have a switch on the seat, brake/clutch, blade engagement. Check your manual for any other hidden switches.

Thanks for all the tips. I finally narrowed it down to some loose connections in the relay system. That would have been bucco bucks for the repair guy to hunt down. Bottom line----It's fixed!
Thanks,
Kupgas