1 - 2 - 7 - 8 Clutch Releases
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.
1 - 2 - 7 - 8 Reverse Control Solenoid
The 1-2-7-8 reverse control solenoid is signaled off allowing S1 VFS SIG fluid to exhaust and the 1278R control valve to shift do to the 1278R control valve spring force. 1278R CLU fluid exhaust into the EX BACKFILL fluid circuit from the release of the 1-2-7-8R clutch assembly plates.