Tractor Repair: MX135 PTO fault codes, screw driver, volt meter

Question
I have a CaseIH MX135 - and the pto quit turning after about 7 seconds after turning it on.  You can trn it off and back on and repeat this over and over and the pto quits every time.  I checked the fault codes - and it is 63.  An idea what that might be??

Answer
Sounds like its a speed sensor. If it has metal on the pickup then it will not sense the speed and shut off the pto. Change the sensor or check it with a volt meter set on ac and run a screw driver over the pick up the voltage should increase the faster you move the screwdriver. If changing it does not solve your problem then you might have a controller going bad or the wiring to the computer has a problem. Start with the sensor then go from there.