G100 Won't Start

I have a 2003 G100 Lawn Tractor that I bought 2 years ago. It's been running great until last week. It won't start, won't crank. The local JD store gave me an electrical service manual. Manual pointed to a bad key switch. I bought a new one. No luck. The manual doesn't say what to do if you replace switch and it still doesn't work. I tried another battery and no luck. Service manual said i should get battery voltage at red wire on key switch in off position. I'm geting 12.75 V. In the run position the yellow wire is supposed to read the same. It doesn't. It drops to 0.9 V. If I remove the battery discharge light bulb the voltage jumps to 1.4 V. If I disconnect the X4 motor connector the voltage jumps to 11.8 V. Connecting the X4 connector back up drops it back to 0.9 V. With the X4 disconnected and the battery light off the hour gauge works but oil light doesn't. Head lights will not work at all. I've checked the seat switch and brake switch and they're good. Any help wil be appreciated. Thanks, Dan