I have a 2001 Z71 Tahoe. Changed out cluster with one from HD truck so I could have transmission temperature gauge. This is a very common swap.
After changing out the cluster I noticed my speedometer was 85% of actual speed. I used a scanner to see the PCM was registering speed correctly.
I'm looking at calibrating the speed in the PCM however, the speed signal is used by many parts of the truck. I'm not sure if I adjust in the PCM if it will affect cruise control, ABS, Airbags, or have any effect on the instrument cluster? I have my programmer hooked up but don't want to tinker too much till I know more about it.
Additionally, I wonder if there's a configuration in the cluster itself. It has a daughter board with processor and EPROM to store odometer (possibly more?) off which the signal is sent to the gauge motor.
Anybody have experience with calibrating the speedometer on this era of GM product?
Thanks,
PS. I have some notes here on work I've already done to diagnose this problem: https://www.tahoeyukonforum.com/thre.../#post-1465157