4T65E - No gear

A friend called during the weekend, while driving on the vacation with the family the gear suddenly disengaged at crusing speed in a slight downhil. After that the transmission would not go into gear in any position. There were no slip, no noise, no visible oil leak nor other symptoms when this happened, just the gear disengaged. The van has now been towed to a local workshop for diagnose.

From what he described to me it seems similar to the thread below, but it was never updated with information on what acctually was the problem:
http://www.automotiveforums.com/vbulletin/showthread.php?t=1020052

On my advise he checked fuse 31, which is feeding the solenoids in the transmission, but it was ok. Since there was no noice and it wasn't in a high torque situation I don't believe there has been a major mecanical failure, rather either loss of electrical power or hydraulic pressure. He have had the common hard shifting issue so maybe that solenoid gave up or the pump. He doesn't have any code reader so I don't know if any has been set.

I'll update you when the workshop has done the initial diagnosis..

My gut feeling is that it's the pump, googling on it I found this very good writeup:
http://helpwrench.com/forums/showthread.php?309-4T65E-Tranny-Lost-all-FWD-GEARS-and-REV-all-the-sudden-NO-CODES

It's also a good description on how to get access to remove the side cover under where the pressure control solenoid is located, which cause the hard shifting issue.