Manual Downshifts
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. 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.