Speedometer not working properly

Tiny
TNPRUIZ
  • MEMBER
  • 2006 PONTIAC G6
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 203,567 MILES
My speedometer says I am going faster than I actually am.
Tuesday, October 9th, 2018 AT 7:43 AM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi and thanks for using 2CarPros.com.

The speedometer in this vehicle is different than the traditional ones. Basically, the body control module (BCM) receives a signal from the wheel speed sensors. Based on that information, it sends a signal to the Instrument Panel Cluster (IPC). Now, if there is a fault with the wheel speed sensor/ vehicle speed sensor (VSS), the main computer will set a diagnostic trouble code indicating a fault. Therefore, the first thing you need to do is scan the computer to determine if there are any related fault codes stored.

Here is a quick video related to using a scanner. I realize most people do not have one, but just in case. If you do not have one, most parts stores will scan the computer for free.

https://youtu.be/YV3TRZwer8k

If there are no faults in the VSS circuit, then either the IPC is bad (speedometer and cluster) or the BCM is bad. I have attached a flow chart for diagnosing the issue. Take a look through it and let me know if you have other questions or need additional help.

Please keep in mind, before you replace any components, always confirm there is not a simple issue such as a loose connection or corrosion on one of the connectors causing issues.

I hope this is helpful.

Take care,
Joe
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Tuesday, October 9th, 2018 AT 6:23 PM

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