Diagnostic Aids

WARNING: This page is about a different car, the 2009 GMC Yukon and 2009 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

A defective transmission output speed sensor (OSS) can cause inaccurate speed reading, creating faulty replicated output speed signal. Also, inspect the OSS for cracks, loose mounting, or damage.
If the speed sensor passes testing, refer to Testing for Intermittent Conditions and Poor Connections .