tranny not shifting to over drive

[sunnyc123abc]

I have a 700r4 and this past weekend i drove it on the free way, and it wouldn't shift into overdrive. It shifted to overdrive fine in june, and since then i haven't drivin it on the freeway till recently and no overdrive. So i change the oil and put in a tranny cooler, and it still doesn't shift to od. So wat could be the problem?

 

[randy88k5]

Well, overdrive gets actuated by the computer one the vehicle speed sensor senses its going the desired speed and the engine is under the desired load. If for some reason your speedometer is not working, the VSS wil have no signal, therefore no overdrive. The VSS is in the back of the instrument cluster for cable driven units.

Other than an external sensor problem, it looks like it would be an internal tranny problem. 700r4s are not known for their longevity, especially in stock form. Adding a cooler is good preventitive maintenence, but not a solution to a problem. So, it might just be that time...

 

[sunnyc123abc]

but i just rebuilt it about a year ago?

 

[gmcjimmy90]

mine used to do that if i didn't use od for a while, just get going about 60mph and manually shift it from drive to od to nutreul then back to od then to drive you may have to do it several times but should free up the valve if it is stuck.

 

[jhellwig]

Make sure that you are getting it into od and not just looking at what the pointer says. In my espirience the pointers never are right. I always count the clicks when I put mine into gear. 3 clicks and you are in od. But even when you count the slick the internals of the tranny vales might be worn and need a little coaxing to get into the right spot to shift.