Circuit/System Description
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The driver shift request (DSR), also known as the TAP Up/Downshift manual shift function, allows the driver to select the desired range of gears for current driving conditions. The DSR shift system is activated when the gear selector is in the manual position. The DSR system is deactivated in all other range positions. When DSR is selected, a signal is sent to the body control module (BCM) and the also to the transmission control module (TCM). Each time a signal is sent, an internal counter in the BCM and TCM increments. Both counters must have the same value. This code sets when the rolling count value of the TCM does not match the same rolling count value sent from the BCM.