So, I bought my blazer 6 months ago and here recently the gauges have gone out of whack, jumping all over.. I have the tach gauge on my cluster. It is usually the speedometer doing it, but the tach gauge started doing it as well and the abs light came on when the tach gauge did it.. then I noticed my abs pump was coming on when I was going at slow speeds barely braking. I removed the fuse to fix that temporarily.. Any idea what is causing the gauges to do this?

 

Poor ground? faulty wiring somewhere?

 

Could it be the speed sensor on the transfer case?