Have a John Deere 304H loader throws code ER04, JD tech says it is parking brake. Have changed parking brake switch many times, it will work for awhile but then locks everything up. Have to turn master switch off for awhile sometimes it takes off sometimes it takes several atttempts. JD said to try new monitor so $2500 later because parking brake light and seat belt light would flicker, everything was working fine for about 10 hours then it started up again. I am so frustrated, changed trans filter/fluid, checked brakes and fluid. Any help would be greatly appreciated, thanks.