Automatic transmission questions

Hi, truck is a '94 C3500 dually, 7.4 gas engine, 4L80E ?? transmission. Just fixed a fast idle problem I was having with the TBI and everything was right again. I then noticed while driving the truck that the trans would not always shift into 3rd gear if I ran the shifter in 3rd. I could bump it up to OD and it would shift fine. This does not happen all the time but has gotten to be 70% of the time. I don't mind using OD but I don't want to pull a load this way so I do some research about TV cables and how to adjust them. I figure I might have something out of adjustment after working on the TBI. Some sources say it is a simple procedure and should actually be done every 6 months to allow for cable stretch while others say don't touch it - it was set at the factory by voodoo and black magic and is not for mere mortals to tamper with. Others indicate the need for a pressure gauge to check line pressures as you drive. I go to look at the cable for some reference and it turns out there isn't one! There is not even a sign of one being on the truck ever.
I research the RPO codes and get MT1 which is the 4L80E and MXO which is MERCHANDISED TRANS AUTO PROVISIONS, O/D - What is that? I look at the trans, count 17 pan bolts, study the pan shape - it looks like a 4L80E except mine has a raised area in the bottom with a drain( I assume ) plug. Is this normal? My real question besides what I have been rambling on about is: Do 4L80E transmissions use a TV cable and if so where does it enter the transmission? Is this a normal setup for a 94 truck? I checked the fluid and it is red just as it should be with no burned smell. If there is no TV cable is there some other adjustment for the 2-3 shift?
Thanks for listening
Transmission experts tell me what you think!
HotRodr56

4l80e e stands or electric controled.
Check your TBI unit how many cables on it??

2 cables. One for the throttle ( gas pedal ) One for the cruise control. So no TV cable required? I see kits offered to correct shifting gremlins etc etc for the 4L80E, any experience with these? I plan to install a temp gauge to monitor the trans but the quirk of D not working all the time kinda bothers me. I put on slightly taller new tires when I got the truck, any way this factors in with the problem?

I would disconnect the neg battery cable for about 5 min and then take it for a hard ride (get into it) to let the ecm relearn the shift points. If that does not work post it here

Thanks Fireplug, BTW thanks for the help on the TBI idle problem. I will give it a test ride and report back.

Thanks,
All seems well after several days of driving and towing. the battery disconnect did the trick.

You are welcome