Fjrst off id like to Introduce myself. My name is Cory, and I'm from from Grass Valley, Ca, 20, and the new owner of a 1994 suburban k1500 silverado. I picked it up for a steal at $400 here locally. But it has its quirks. One of which is that the tranny doesn't shift out of second gear. I've read numerous forums, and such online and direct me to many different possibilities. I don't want to have to tear apart and rebuild the tranny but if I have to, in the end I will. I'm very mechanically inclined to the point that if I know what's wrong I can r&r it.(Mechanic, Not a Technitian) But diagnosis isn't my thing, nor do I have access to the proper tools such as code readers and such. I've read that it could be a shift solenoid, or a 3-4 clutch, or even a forward sprag. The last two would require me tearing the tranny out and replacing from within, and the first would just require a messy under the truck bit.

Also I might add that my speedometer doesn't work right either that would lead me to believe the vss or vssb might be bad or a surrounding part. My tachometer is spot on, just not the speedometer. Speedo doesn't work at all until around 2,400 rpms in second gear and it bounces around like crazy, which would also make sense as to why its not shifting as I know these vehicles shift when they're told to by the computer which reads the speedometer and times the shifts from there. I havent gotten underneath it and looked around yet for loose connections, bad grounds, etc.

The guy I bought it from had regular maintenance done, and it was his daily driver up until about two weeks ago when out of nowhere while driving he pulled from a stop and it wouldn't shift out of second.

It drives fine in gear selection 1, 2, and R but if I put it in D or OD it acts as if its in neutral.

I do apologize for the long posting, but I felt it would be necessary to give as much information as possible to help further with anyone's input.

I look forward to any help and am greatful to be part of the Chevrolet forum community!! Thank you and have a great day!!

 

Staying in second gear is most likely "limp mode." The computer sensed a problem, and it shut things down to prevent further damage. Is the check engine light on? You need to run some diagnostics to see what's wrong.

 

Yes cel came on while driving it home after purchase yesterday, after that I noticed it only ran in second, before that, it ran fine in first and second only but only when gear selection 2. Is there a way to pull the codes without a reader, like blinking lights and whatnot??

 

Most of the auto parts chains will read the codes for you.

 

So I used a jumper wire to jump slot a and b to go into diagnostic mode and pulled codes 16, and 72.

I did some searching on the old interweb and:
16 came back with: vehicle speed buffer.
72 said: trans output speed sensor.

Correct me if I'm wrong, also please give details as to what they might translate into, please and thank you.