Manual Downshifts
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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.