I have a 2001 4X4 Blazer. My ABS light and red brake light are on. The speedometer is very erratic. Sometimes the automatic transmission will not shift. I have checked both front abs wheel sensors. They are putting out over 350mv's. I measured this at the ABS module under the hood. The brake fluid level is good. I removed the Vehicle speed sensor. It measures over 1M ohm resistance. If I set my meter to millivolts ac and pass a screwdriver near the end of the sensor it does produce a reading. From what I have read the resistance of the coil in this sensor should be around 1000 ohms. Which would make sense to me. I checked the two wires for continuity from the speed sensor to the VCM module and I get close to zero ohms. So they are good. I had read that some people have had cold solder joints in the ABS module. So I checked mine and the solder joints all look good. With the 60amp fuse pulled that supplies power to the ABS module I still get an erratic speedometer indication. So I don't think the problem is the ABS module. Hope this is enough info for a diagnosis from someone. Thanks