7 hours ago, djwarner said:

A bad or disconnected vacuum modulator will disrupt proper shifting. Remember a vacuum line has two ends as well as the hollow tube. I would first verify the vacuum hose, then replace the modulator before tearing into the AT again.

There is no internal electronics in the AT. The only wiring is a switch for the starter enable and for the backup lights.

When I detach vacuum line from modulator then I cannot shift even to the third gear and when I attach it it shifts to third gear and skips the second one !  it leads me to the conclusion that it works !  Or could I be wrong ?

Downshift solenoid is working as it clicks when I connect it to battery but its role seems to be just to shift to lower gear when pressing full throttle !

Edited March 16, 20206 yr by Darko

Did you try the solutions offered in the document?

I tried to check everything I can while the transmission is on the car !

That's great that you tried but which ones did you do and what did you find?  I see these as the ones to do, based on what you said is happening.

Manual control valve is ok , checked 

Governor valve -  I only checked downshift solenoid and vacuum modulator and they are ok although solenoid has has nothing to do with it . I cannot check anything inside the gearbox as it is now installed on the vehicle. Do you know how to check governor valve ?

New oil is in the system , and sufficient amount , there is no leakage 

Transmission air check - I only checked vacuum that goes from engine and it is ok 

Band brake is inside gearbox and cannot check 

 

If you have any suggestion what I can do while the gearbox is assembled and on the car let me know !