Manual Downshifts
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.
Manual downshift testing is not required since all vehicles equipped with the 6L45/50/80/90 are also equipped with some form of Driver Shift Control(DSC). The TCM will automatically override DSC downshifts to protect the transmission from damage.
Coasting Downshifts
- Place the gear selector in the DRIVE position.
- Accelerate the vehicle to 6th gear with the TCC applied.
- Release the throttle and apply the brakes
- Verify that the downshifts occur as commanded by monitoring gear ratio, which should change after commanded gear changes.