1994 GMC Truck jumping speedometer

1994 GMC TRUCK
158,000 MILES • V8 • 4WD • MANUAL
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JAMESERVEN
  • MEMBER
  • 1 POST
My speedometer started jumping up and down.
It would read correctly at 60 mph and then start jumping between 20 and 45 mph then it would read fine. How do I know if it is my vehicle speed sensor or my speedometer? Could it be something else?
Thanks
May 1, 2010 at 8:29 PM
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HMAC300
  • ✓ASE Certified Mechanic
  • 48,601 POSTS
  • ASE Certified Mechanic
it could be your speed sensor, you can check the ohms to see if it's grounding out or having to high of ohms. Or it could be the speedo or the wiring or connections are in poor shape. I'd start at teh bottom as that is more in the weather than the speedo head.
May 26, 2010 at 3:44 PM
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