Speedometer begins displaying inaccurate numbers around 10 MPH?

1999 CHEVROLET 1500
17,500 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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CHARLESTUCK
  • MEMBER
  • 66 POSTS
My speedometer begins displaying inaccurate numbers around 10 MPH (as soon as I start rolling) and gets increasingly faster until the speed displayed is 50 MPH faster than the actual speed. At 50 MPH, my speedometer is displaying around 100. In short, the faster I go, the more inaccurate the speedometer. I use my GPS speed function to compare the speed.
Dec 29, 2024 at 11:43 PM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,246 POSTS
Hi,

This could be related to a faulty speed sensor or even the instrument cluster is failing.

What I need to know is this. I need you to have the computer scanned to see if there is a P0500 or a P0501. If that is present, it is likely related to the sensor. If it isn't, we need to check wiring or issues to determine if the IP is actually.

Oftentimes, a parts store will scan the computer for you free of charge. Is it possible for you to have that done? Here is a link showing what I would prefer to have done if possible. If you can't have the entire can-bus checked, I know places like AutoZone have scan tools that could retrieve the codes.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know.

Joe
Dec 30, 2024 at 12:40 PM
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