transmission

[Jojo47ty]

I have a 88 ram 50 with a 2.6L auto trans it wont go into 4 gear unless i let off the pedal but when i do it wont stay in so it drops back into 3 and the rpms go back up it does this at 45 mph so idk what i could do for it please tell me if u know any thing.

[camoit]

Have you changed the oil and filter?
Have you checked the kick down linkage for proper adjustment?

[mashtdi]

Does this happen only when the truck is cold? Like when you first start out in the morning? Or all the time?

[Jojo47ty]

it happens even after it warm so i dont really know

[royster]

Do those transmissions have any vacuum modules that help operate it? On some older American transmissions, a loose or disconnected vacuum line prevented shifting. Since I have a 5-speed manual, I cannot say, but it's an idea to consider.

[camoit]

I know there is a linkage adjustment that is ever so important to get correct or it will not go into high gear. Thats where I would start.

[pennyman1]

with the throttle at rest, adjust the kickdown cable so there is a slight amount of slack in it, then try it and see how it shifts. It sounds like it is too tight and is pulling the lever too far too soon. Also check to make sure the kickdown lever on the tranny is not sticking, as that will cause this problem too.Had a similar problem with my 88 ram 50 sportcab, and also had the sticking lever on a 1991 dogkota (yes i spelled it that way on purpose) that the kickdown stuck until I installed a carb return spring on it.