speedometer is erratic transmission shifting rough

How long since you had a tranny service?

My 2000yr 2500 Express [5.7 with 4L80 Gb.] has also has erratic speedo and transmission shifting issues. Notes: 1. Shifts early to highest gear..doing 30-35 and speedo reading 60+ . 2. No Codes showing on scanner. No dash check engine light or other warning light. 3. I Installed a New VSS 'Vehicle Speed Sensor' ($59) but it didn't solve the problem.but usually is the cause. 4. Wiring looks okay..but now having to check from tranny to VCM. 5. Very surprised there were No codes/ DTC's. 6. So currently still trying to figure out... 7. Got the books out to work thru. other potential causes..not that the GM Manual helps much! Other Possibilities: ???? a, Maybe could be corrosion on a connector somewhere? causing the VCM to not get the correct voltage/signal. Input appreciated.

Any movement on this problem? I'm having the same issues on my 2002 Chevy Express 3500. I've replaced the ECM, VSS, Ground Strap all to no avail.

may be mositure in computer,mine does same thing after it rains,I drive it shifting the gears,speedometer jumps over to 100 shuts engine off when your going about 45,going reprogram speed limiter,and just keep on driving it,just pull lawn mower around with it,haul off trash,not worth new computer

I have to 2000 3500 express van and I have the answer. Same problem. This transmission has two sensors. Everyone knows about the rear sensor but for some reason the front sensor is a secret. It's the input sensor and looks like the rear one. It is different and it seems only the transmission guys know about it. It's called a turbine sensor and since it was replaced my truck is back to normal. Again don't replace it with the same sensor as the output or rear sensor. The parts guys have the wrong information. Good luck.