speedometer is erratic transmission shifting rough

Asked by Sep 06, 2015 at 10:23 AM about the 1999 Chevrolet Express G3500 RWD

Question type: Maintenance & Repair

4 Answers


How long since you had a tranny service?

2 of 2 people found this helpful.

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.

9 of 9 people found this helpful.

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.

2 of 2 people found this helpful.

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

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