Chevrolet Silverado / GMC Sierra. Manual — part 745

Fig. 16: Identifying Black Supply Hose & Clear Waste Hose
Courtesy of GENERAL MOTORS CORP.

2. Connect the black supply hose (1) to the return line, top connector of the transmission, and

the clear waste hose (2) to the feed line, bottom connector of the transmission, to the vehicle
cooler lines. This is the reverse flow - backflush direction.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Fig. 17: Setting Main Function Switch To FLUSH Position
Courtesy of GENERAL MOTORS CORP.

3. Turn the main function switch to the FLUSH position. Allow the machine to operate for 30

seconds.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Fig. 18: Setting Main Function Switch To IDLE Position
Courtesy of GENERAL MOTORS CORP.

4. Turn the main function switch to the IDLE position and allow the supply vessel pressure to

dissipate.

FORWARD FLUSH

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado