Regardless of throttle position my 1-2 shifts happen at 5 mph or less. Sometimes it will start in 2nd, drop to 1st, then immediately shift back to 2nd. I've adjusted the TV cable to no effect. Manually shifting the trans results in perfect operation. The trans was rebuilt by a local shop who screwed me over pretty good so I'm not exactly sure what's actually been done to it. The VB should have a DTT shift kit still in it, which I had installed about a year before the rebuild. My 1-2 shifts have always been the way I described, even before the shift kit and remained the same after the rebuild. During the build all of the electronics in the VB were supposed to be replaced but I have a strong suspicion they weren't. After some research it seems a faulty pressure transducer may be the cause. Does it sound like I'm on the right track? 

 

I'm a mechanic by trade but I've never rebuilt an automatic transmission and honestly wasn't that familiar with their operation. I've been doing all I can to learn how they function by watching videos and digesting as much literature as possible.

I would say you should replace all the solenoids and such as a first step.  I think you are on the right track.

Just found out my neighbor has a scan tool with live data stream so I'm going to see what the sensors are doing before dropping the pan. I'll post up what I find. 

Well I found the cause of the 1-2 shift issue, it was the 100 ohm resistor that is sometimes used to keep the trans from going in to limp mode after line pressure is increased. Seems the truck was never tested to see if it actually needed the resistor, which it didn't. With it removed I was able to adjust the shift points via the TV cable. Now 1-2 shifts happen around 17 mph and 2-3 shifts around 30 mph or so. 3-4 is around 40 mph and lockup around 48 mph since wiring in a pot to replace the TPS. 

great to hear.

I spoke too soon. It ran fine for a whIle but now the throttle gets hard to push down because the TV lever is fighting back. I'm going to put the resistor back in and see what happens. I'm really starting to not like this trans.

oddy enough my trans doesn't need the resistor.  must be in the pcm

Figured I'd update this in case this thread comes up in a search. I hate it when people never post what the solution to their problem was. 

Long story short I installed a new valve body and my trans works better than it EVER has. The full story can be found here.