700 R4 wont go into overdrive?

88' 700 R4 i just replaced the pump seels in this tranny and got it put it back together and filled full of tranny fluid and now ive got 1st 2nd and D but the overdrive wont work ?? tranny shifts fine... also this is a truck that used to have a computer and im still using the computer to run in the tank fuel pump but now its carbeurated so pretty much all the rest of the electrical for the computer is gone... could it be that the computer is in a "limp in mode" and is still talking to the tranny saying "that gear is too fast for all the problems im seeing"?? haha or whats going on here??
thanks in advance for any and all help!!

did 88 yse a tv cable? or was that earlier, I can'y remember.

All 700s have the cable..If they don't they are 4L60..Pretty sure that started in 92

thanks for correcting me, I couldn't remember. But I do remember how important that cables adjustment is for the use and life of that tranny.

im pretty positive ive got it hooked up right .... because i put the selector on the overdrive D when im sitting inside the truck and it just acts as neutral

If the cable is adjusted correctly. Will it shift manually ? The band is on in second and fourth and a servo brings it on . Did you change the front pump gasket?? Let me know

yeah i changed out the front pump gasket due to it pouring out ATF daily....
thanks and look forward to hearing from you