Chevrolet Silverado / GMC Sierra. Manual - part 748
NO DRIVE OR REVERSE GEAR
NO FIRST GEAR
Input Sun Gear Thrust Bearing
(54)
Inspect the bearing for wear or damage.
Input Sun Gear (53)
Inspect for spline wear or damage.
Input Carrier Assembly (52)
Inspect carrier assembly for damaged pinion gears, thrust
washers, pins, and rollers.
Turbine Shaft Thrust Bearing
Assembly (57)
Inspect the bearing for wear or damage.
Fluid Filter Assembly (26)
Inspect for damaged or restricted fluid filter assembly
(26).
Inspect for damaged fluid filter seal assembly (25) or
improper sealing interface, leaks, and fluid aeration.
Automatic Transmission Fluid
Pump Seal (5)
Inspect for worn or damaged seal.
Checks
Causes
4-5-6 (with Turbine Shaft)
Clutch Assembly (56)
Inspect for damaged 4-5-6 clutch (with turbine shaft)
housing assembly (441).
Inspect for damaged or distorted turbine shaft.
1-2-3-4 Clutch (with Output
Carrier Inner Sun Gear Shaft)
Hub Assembly (61)
Inspect for damaged or distorted shaft on hub assembly.
2-6 and 3-5-R Clutch (with
Output Carrier Outer Sun Gear
Shaft) Hub Assembly (64)
Inspect for damaged or distorted shaft on hub
assembly.
Inspect the output carrier inner sun gear shaft
bushings (60 and 62) for damage or wear.
Checks
Causes
Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)
Inspect for damaged low clutch sprag assembly (467).
Holding the sprag assembly with the retaining ring
facing up, and the inner race of the sprag assembly
fixed, the outer race should freewheel
counterclockwise.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
NO FIRST AND REVERSE GEARS
HARSH, SOFT, DELAYED OR SLIPPING FIRST OR REVERSE GEAR
Inspect for cut, worn, or damaged low clutch sprag
seal (468).
Checks
Causes
Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)
Inspect for damaged or worn low and reverse clutch
plates (463 and 465).
Inspect for damaged low and reverse clutch backing
plate (462). Inspect for worn splines on backing
plate.
Inspect for damaged low and reverse clutch backing
plate retaining ring (461).
Inspect for damaged low and reverse clutch piston
assembly (470), spring (469), spring retaining ring
(466), and center support assembly (459).
Inspect for damaged low clutch sprag assembly (467).
Holding the sprag assembly with the retaining ring
facing up, and the inner race of the sprag assembly
fixed, the outer race should freewheel
counterclockwise.
Inspect for cut, worn, or damaged low clutch sprag
seal (468).
Output Carrier Assembly (68)
Inspect for damaged or stripped splines on the output
carrier assembly.
Checks
Causes
Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)
Inspect for damaged or worn low and reverse clutch
plates (463 and 465).
Inspect for damaged low and reverse clutch backing
plate (462). Inspect for worn splines on backing
plate.
Inspect for damaged low and reverse clutch backing
plate retaining ring (461).
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
STUCK IN FIRST OR REVERSE GEAR
NO FIRST, SECOND, THIRD, AND FOURTH GEAR
Inspect for damaged low and reverse clutch piston
assembly (470), spring (469), spring retaining ring
(466), and center support assembly (459).
Inspect for damaged low clutch sprag assembly (467).
Holding the sprag assembly with the retaining ring
facing up, and the inner race of the sprag assembly
fixed, the outer race should freewheel
counterclockwise.
Inspect for cut, worn, or damaged low clutch sprag
seal (468).
Checks
Causes
Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)
Inspect for damaged or worn low and reverse clutch
plates (463 and 465).
Inspect for damaged low and reverse clutch backing
plate (462). Inspect for worn splines on backing
plate.
Inspect for damaged low and reverse clutch backing
plate retaining ring (461).
Inspect for damaged low and reverse clutch piston
assembly (470), spring (469), spring retaining ring
(466), and center support assembly (459).
Inspect for damaged low clutch sprag assembly (467).
Holding the sprag assembly with the retaining ring
facing up, and the inner race of the sprag assembly
fixed, the outer race should freewheel
counterclockwise.
Inspect for cut, worn, or damaged low clutch sprag
seal (468).
Checks
Causes
1-2-3-4 and 3-5-R Clutch
Assembly (51)
Inspect for damaged or worn 1-2-3-4 clutch plates
(408-410).
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
HARSH, SOFT, DELAYED OR SLIPPING 1-2-3-4 SHIFT
NO FIRST, SECOND, THIRD, FOURTH, FIFTH, OR REVERSE GEAR
Inspect for damaged 1-2-3-4 clutch piston (414),
piston housing (417), spring (413), and dam assembly
(412).
Inspect for damaged 1-2-3-4 clutch piston dam
retaining ring (411).
Inspect for cut, worn, or damaged 1-2-3-4 clutch
piston seal (416), inner seal (423), and housing seals
(424 and 425).
Inspect for improper selective 1-2-3-4 clutch backing
plate retaining ring (429).
Inspect for damaged 1-2-3-4 clutch backing plate
(407). Inspect for worn splines on the backing plate.
1-2-3-4 Clutch (with Output
Carrier Inner Sun Gear Shaft)
Hub Assembly (61)
Inspect for damaged splines on the hub assembly.
Checks
Causes
1-2-3-4 and 3-5-R Clutch
Assembly (51)
Inspect for damaged or worn 1-2-3-4 clutch plates
(408-410).
Inspect for damaged 1-2-3-4 clutch piston (414),
piston housing (417), spring (413), and dam assembly
(412).
Inspect for damaged 1-2-3-4 clutch piston dam
retaining ring (411).
Inspect for cut, worn, or damaged 1-2-3-4 clutch
piston seal (416), inner seal (423), and housing seals
(424 and 425).
Inspect for improper selective 1-2-3-4 clutch backing
plate retaining ring (429).
Inspect for damaged 1-2-3-4 clutch backing plate
(407). Inspect for worn splines on the backing plate.
Checks
Causes
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado