Speedometer not accurate in the slightest

[justinsaunders]

I just purchased a 97 c1500 I’ve had a few other gmt400s in the past and I’ve had this same problem before before I swapped the motor in my single cab but after the swap it fixed itself. The speedometer will go up in speed inaccurately and when letting off the throttle it will decelerate inaccurately as well. I don’t know how to explain it exactly but I’ve changed out the wheel speed sensor as well and it didn’t change anything. I’ll comment with a video as soon as I can if anyone could help it would be berry appreciated thank you

 

[sewlow]

Stock/aftermarket equivalent height tires or are they over/under sized?
Rear gear swapped?
Any other small quirks? Poor grounds can cause all kinds of seemingly unrelated probs.

 

[GoToGuy]

Speedo gets signal from trans. Wheel speed sensor for?

 

[Dariusz Salomon]

Mine is inacurate too-stepper motors may be the culprit as far as I know. You can try to replace them,replace the cluster or learn the speeds driving on gps and live with it. I for now chose the last option.
Also there's this

How to Recalibrate/adjust your speedometer

This thread will provide detailed instructions for those with a 1992-1998 Gm pickup truck, with either 2wd or 4wd who wish to recalibrate there VSSB(vehicle speed sensor Buffer). This should be done when gearing ratio or tire sizes are changed to keep both your speedometer and Odometer correct...

www.thetruckstop.us