Circuit Description
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Module (TCM) uses input from the turbine speed sensor and the output speed sensor to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current gear range.
This is a type "A" DTC.