Circuit/System Description
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The drivers shift request (DSR), also known as the TAP Shift, allows the driver to manually shift gears by pressing the plus (+) or minus (-) buttons and select the desired range of gears for current driving conditions by using the DSR shift switch located on the automatic transmission gear shift lever. Pushing the plus (+) switch will command an upshift and pushing the minus (-) switch will command a downshift. A 12 V reference voltage flows from the body control module (BCM) through the DSR switch resistor array to the BCM. The DSR shift system is activated when the gear selector is in the Manual (M) position. The DSR system is deactivated in all other range positions.