My speedometer reads wrong. I can be traveling about 60 mph and it reads 90 mph. When it first happened, I was doing about 75 mph then my speedometer just started climbing higher. My actual speed did not increase. When I come to a complete stop, it reads between 30 and 40 mph. I drive a 2005 GMC Sierra, 1/2 ton, extended cab. What are the possible causes for my problem.

. Check the connection to the Variable Speed Sensor (VSS).

. Replace the VSS.

. Check all under dash and under hood fuses with a test light or multimeter.

. Replace the speedometer.