There are three common reasons for this in cars equipped with electronic speedo gauges.
1- A dirty or faulty ground connection on the instument cluster harness. Finding the harness and a wire that grounds to the firewall is a starting point. You may have to improvise a new ground from a point where the ground wire is accessible for troubleshooting purposes if the actual firewall connection is behind the dash or console.
2- A dirty speed sensor or connector. This is usually mounted on the transmission. Try removing and cleaning the sensor and/or connector. This part is usually cheaper to replace than a gauge cluster
3- Poor gauge cluster connections or gauge failure: Try just removing the cluster and cleaning the contacts at the back of the cluster with contact cleaner making sure no cleaner gets on the plastic or in the gauge(s). If this doesn't fix the issue, replacing the cluster may be necessary.
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Thursday, December 24th, 2009 AT 10:24 PM