Ok so this problem started after I installed a new y pipe and installed new 02 sensors.
How it started was the speedo and tach would flick off and come right back on in a second, happen once a day then twice then three times. then became constant and when it was contant 1st and OD wouldnt engage even if you tried to do it manually. I have already done lots of research on this and people all say its your speed sensor on the transfer case, So I replaced one with a junkyard one and it made no difference same thing, tried with another junkyard one and same thing, So I went and bought the part for 160$ which I didnt want to do and still im having the problem. Just wondering what else I could try and replace. or could I have possibly pinched some wires when I was putting the y pipe on, Only wires I noticed for the y pipe was the o2 sensors though.
Any input advice is appreaciated. This Jimmy was already hard on gas and now its just getting ridiculous.

 

Sure sounds like wirers someplace in that speed sensor circut

 

i know loseing 1st and 4th is a sign of a failed shift solenoid. BUT loseing speedo and tach sounds like a computer issue or connector coming loose

 

ya I tried finding where the speed sensor harness runs to, from what i felt above the transfer case correct me if im wrong, but does it run over top the transfer case to the passenger side then into a large harness covered with wire loom?
Edit- where would it break off at again after the bunch of wires in the loom so I can see if there is a short somewheres?
Aswell the speedo and 1st and OD will sometimes kick in for a little while maybe once a week it happens, works great driving from point a to point b, but after that it just goes back to how it was and if im driving at a high speed say 80km/hr shut the truck off then turn it back on right quick the speedo and tach turns on, gears are still the same but I get a speed reading. but as soon as I hit a stop light it will shut right back off again.

 

if the speed sensor was the problem it wouldn't want to shift gears or it would go into limp mode which means only 3rd gear.

This sounds like more than just the speed sensor. The speed sensor should be towards the back of the transfercase. Make sure the large connection on the driverside of the trans is secure

 

I just fixed the same problem on my 1997 LT 4x4. It was the veh speed sensor on the transfer case. $69 part. It runs perfect now