JD 6400 Low Transmission/Hydraulic pressure

[benyost99]

Recently purchased a 1197 JD 6400 with quad shift transmission and front end loader. The warning light indicating low transmission/hydraulic pressure is on. Fluid levels are fine. I'm guessing either bad sensor, clogged screen restricting flow, or worst case...bad pump. Looking for help on where to start. I need to get the manuals still so I'm a little in the dark right now. I'm really hoping it is something simple. 3700 hours on the tractor. Any help would be greatly appreciated.
Thanks,
Ben

 

[Tx Jim]

I'd suggest to change hy filter.

 

[jd110]

TxJim, assuming the filter restriction switch and light are working, the filter is probably OK. The Trans pressure sensors are noted for failing occasionally, especially the original style. It is a good idea to replace the filter first to be sure, but I am betting on a bad sensor. It would be #12 in the diagram. The diagram pictures the new style sensor. The original one looks different. The hex portion for the wrench is the largest part. It will take a 30 mm wrench or socket to remove. The new one takes a 9/16" wrench. It is on the front valve housing of the transmission. If you have mfwd, it is a little more challenging to change because of the driveshaft in the way.

 

[Tx Jim]

jd110
You're probably correct but I was taught to do the easiest things first and changing the filter is easy compare to other things.

 

[benyost99]

Thanks for the replies. It was supposedly just serviced with new filters/fluid, but that is a pretty simple thing to change just in case. I'll track down the sensor and try that next.