problems with 1996 4L60e trans shifting

[acollins2187]

I have a 1996 Z71 truck with a 5.7 vortec 350 motor and a 4L60e transmission that has some shifting problems it will not shift and we pluged the computer tester up to the truck and it said it was a PO785 shift/timing solenoid malfunction we changed the shift/timing solenoid and did not fix it which we think the shifting solenoid is on the driver side but we are not sure if this one is it because there is two just alike.
The problem with the truck is when you first start out in the truck it works fine till it changes through all the gears then it will not downshift by its self you can downshift it manually from third to second but does not have 1st gear or overdrive. You can turn the truck off and let it sit for a while and it will do fine and shift up but not down without manually.. If anyone has any information to help with the problem we would really really appreciate it...

NEED HELP

[megamaxtrannys]

can you give me the exact code its setting , and ill see if i can assist you .
megamax

[acollins2187]

thank you the code was po785 but i got it fixed it was a 2/3 shifter solenoid .. thanks

[acollins2187]

after changing the 2-3 solenoid the transmission worked fine for about 50 miles and now it has 1 and 2 gear but no 3 gear it trys to go in third gear but the rpm will go up but the transmission does not make the truck go any one got any answers if you do i would appreciate them very much..

[megamaxtrannys]

1-2 second shift normal , then where the third gear shift should be the tranny neutrals , is my asumption of what your trying to say , And unfortunatly the is a mechanical failure , 3-4 clutch pack has burned or drum broken . to verify this unplu harness from tranny , attempt to drive , if the 3-4 clutch is bad the car will feel like its in first if its not bad it will be very slugish like in a higher gear , the default gear for the 4l60e with harness unplugged is third gear .
megamax
sorry to give bad news