I HAVE A 96 BLAZER AND I WAS DRIVING AND ALL OF THE SUDDEN THE SPEEDOMETER STOPPED WRKIN AND IT WONT SHIFT. I CHECKED THE CODE AND IT WAS THE VSS. SO I REPLACED THE VSS ON THE TAIL SHAFT OF THE TRANSFER CASE AND NOTHING CHANGED. CHECKED ALL THE WIRES AND THEY ARE ALL GOOD. NOW I AM BEING TOLD THERE IS A VSS ON THE INSIDE IF THE TRANNY THAT I NEED TO REPLACE IS THIS TRUE? IF SO HOW DO I GET TO IT? PLEASE HELP

 

I've never heard of a VSS inside the trans, I'm not 100% sure if there's an input shaft speed sensor on these trans' (I assume there is because the will detect slip and throw a code) but i would think that IF there is then that's what they meant.

Speedo not working sounds like the VSS, you say you checked all the wiring, what procedure did you use to check the wiring. Simply looking at it isn't enough. Did you ohm out the wires from end to end? Check the connectors in both ends of the harness? Have you checked wiring diagrams and schematics and checked for proper voltages and grounds on the pins?

When you say it wont shift does it feel sluggish pulling out like it's stuck in 2nd gear? If so it is in limp mode. Limp mode can be caused by various things, a bad connection on the transmission or PCM would be one thing, a blown PCM fuse (i THINK it might be the same as the cigar lighter fuse but i'm not 100% sure on that). Check engine light on? I know if any of the shift solenoids fail the tests the PCM throws at it a certain number of times it will go into limp mode as well.

 

*Moved to 2nd Gen Tech* - Please read the descriptions of the forum and choose the forum that most appropriately aligns with the topic you intend to post. Also, DO NOT post the same question over and over again in multiple forum sections.

You have a problem with the VSS (vehicle speed sensor). The speedo not working is a dead give away. Are you sure you checked the appropriate wires between the PCM and the VSS?