Tractor Repair: Case-IH 5250 Transimission, speed signals, sensor circuit

Question
My dad has a 5250 that will occasionally loose the powershift gears and go into low.  The tractor will continue to work but the hydraulic light on the dash will light up and the powershift gear selection will no longer work.  If he then turns the tractor off and starts it again it will then work for some amount of time.  Not sure what to look for, can you help?  Thanks,  Andy

Answer
Hello,

  When the problem occurs and the light comes on, hold the clutch pedal down and count the number of flashes of the light on the left side of the dash.  The number of flashes is a code that tells what to look for.  It's usually a pressure switch problem, but could be a number of other things such as a wiring problem or a relay, and of course, a possible internal problem.  It sometimes requires pressure gauges to be installed on the powershift control valve to diagnose the problem.  If there is a leaking power shift clutch, the gauges will tell you.  Sometimes there's a pattern that you may notice that will help to narrow it down.  For instance, if the problem always occurs when shifting from 2nd to 3rd, but not from 4th to 3rd, and the number of light flashes indicates a problem with the off going pressure switch, then #2 pressure switch is bad.

Here is what the flashes mean:

1 flash:  no or multiple speed signals from shift switch.
2 flashes:  offgoing clutch pressure not detected.
3 flashes:  temperature sensor circuit shorted or open.
4 flashes:  solenoid circuit shorted.
5 flashes:  oncoming clutch pressure not detected.
6 flashes:  no or multiple clutch pressures detected.

Here is some info:   http://books.google.com/books?id=UsJyQYkqDoAC&pg=PA68&lpg=PA68&dq=maxxum+powersh...

                 good luck,

                       Arnie