1998 Chevy Silverado V8 Four Wheel Drive Automatic 115000 miles
My friend has a '98 chev. Silverado w/ 4 wheel drive. The speedometer jumps to 35 or 40 mph when it gets over 3 to 5 mph, & to 70 mph when driving at aprox. 35 to 40 mph. It's as though it wants to register double the actual mph. Is this an indication of a faulty or bad speed sensor located on the transmission? &Amp; What is the procedure for replacement? I noticed what looks like a blue piece of plastic around the sensor at the entry of the hole where it is screwed into. Is this a lock system that requires a special tool for removal and replacement? Or is it just a secondary piece to ensure that the sensor does not back itself out from vibration? Any input or information on this would be greatly appreciated. Thanks R.N.