Chevrolet Silverado / GMC Sierra. Service manual — part 749

NO FIRST, SECOND, SIXTH, OR REVERSE GEAR

NO SECOND AND SIXTH GEAR

HARSH, SOFT, DELAYED OR SLIPPING SECOND OR SIXTH GEAR

1-2-3-4 and 3-5-R Clutch
Assembly (51)

Inspect for improper selective 3-5-R clutch backing
plate retaining ring (400).

Inspect for improper selective 1-2-3-4 clutch backing
plate retaining ring (429).

Inspect for worn or damaged clutch bearing (428).

Checks

Causes

Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)

Inspect for a damaged center support assembly (459).

Inspect for worn or damaged output carrier outer sun
gear shaft front and rear bushing (458 and 460).

Center Support Retaining Ring
(66)

Inspect for damage.

Output Carrier Assembly (68)

Inspect for a worn or damaged center support roller
bearing assembly (485).

2-6 and 3-5-R Clutch Hub
Thrust Bearing Assembly (65)

Inspect the bearing for wear or damage.

Checks

Causes

Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)

Inspect for damaged or worn 2-6 clutch plates (452
and 454).

Inspect for damaged 2-6 clutch backing plate (451).
Inspect for worn splines on backing plate.

Inspect for damaged 2-6 clutch backing plate
retaining ring (450).

Inspect for damaged 2-6 clutch piston assembly
(457), spring (456), retaining ring (455), and center
support assembly (459).

Checks

Causes

Center (with 2-6 Low and

Inspect for damaged or worn 2-6 clutch plates (452

2008 Chevrolet Silverado 1500

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

Sierra & Silverado

STUCK IN SECOND OR SIXTH GEAR

VIBRATION IN SECOND, THIRD, FOURTH, FIFTH, OR SIXTH GEAR

NO THIRD, FIFTH, AND REVERSE GEAR

Reverse Clutch) Support
Assembly (67)

and 454).

Inspect for damaged 2-6 clutch backing plate (451).
Inspect for worn splines on backing plate.

Inspect for damaged 2-6 clutch backing plate
retaining ring (450).

Inspect for damaged 2-6 clutch piston assembly
(457), spring (456), retaining ring (455), and center
support assembly (459).

Checks

Causes

Center (with 2-6 Low and
Reverse Clutch) Support
Assembly (67)

Inspect for damaged or worn 2-6 clutch plates (452
and 454).

Inspect for damaged 2-6 clutch backing plate (451).
Inspect for worn splines on backing plate.

Inspect for damaged 2-6 clutch backing plate
retaining ring (450).

Inspect for damaged 2-6 clutch piston assembly
(457), spring (456), retaining ring (455), and center
support assembly (459).

Checks

Causes

4-5-6 Clutch (with Output
Carrier Shaft and Dampener)
Hub Assembly (58)

Inspect hub assembly (475), dampener (476), and apply
plate (477) for wear or damage.

Checks

Causes

1-2-3-4 and 3-5-R Clutch
Assembly (51)

Inspect for damaged or worn 3-5-R clutch plates
(402-404).

Inspect for damaged 3-5-R clutch piston (421), apply
ring (405), and spring (420).

2008 Chevrolet Silverado 1500

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

Sierra & Silverado

HARSH, SOFT, DELAYED OR SLIPPING THIRD, FIFTH, OR REVERSE GEAR

NO FOURTH, FIFTH, AND SIXTH GEAR

Inspect for cut, worn, or damaged 3-5-R clutch piston
dam O-ring seal (418), inner seal (419), and outer
seal (422).

Inspect for improper selective 3-5-R clutch backing
plate retaining ring (400).

Inspect for damaged 3-5-R clutch backing plate
(401). Inspect for worn splines on the backing plate.

Control Valve Upper Body
Assembly

Inspect for a worn, sticking or damaged 3-5 reverse clutch
regulator valve and spring. Inspect the valve bore for
debris or scoring.

Checks

Causes

1-2-3-4 and 3-5-R Clutch
Assembly (51)

Inspect for damaged or worn 3-5-R clutch plates
(402-404).

Inspect for damaged 3-5-R clutch piston (421), apply
ring (405), and spring (420).

Inspect for cut, worn, or damaged 3-5-R clutch piston
dam O-ring seal (418), inner seal (419), and outer
seal (422).

Inspect for improper selective 3-5-R clutch backing
plate retaining ring (400).

Inspect for damaged 3-5-R clutch backing plate
(401). Inspect for worn splines on the backing plate.

Control Valve Upper Body
Assembly

Inspect for a worn, sticking or damaged 3-5 reverse clutch
regulator valve and spring. Inspect the valve bore for
debris or scoring.

Checks

Causes

4-5-6 (with Turbine Shaft)
Clutch Assembly (56)

Inspect for damaged or worn clutch plates (433-435).

Inspect for damaged piston (439), piston dam (437),
dam retaining ring (436), and clutch spring (438).

Inspect for improper selective 4-5-6 clutch backing

2008 Chevrolet Silverado 1500

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

Sierra & Silverado

HARSH, SOFT, DELAYED OR SLIPPING 4-5-6 SHIFT

NO TORQUE CONVERTER CLUTCH APPLY

plate retaining ring (431).

Inspect for cut, worn, or damaged turbine shaft fluid
seal rings (442).

Inspect for damaged or distorted turbine shaft.

Control Valve Upper Body
Assembly (304)

Inspect the 1/Reverse band and 4-5-6 clutch regulator
valve (327) and spring (326) for wear or damage.

4-5-6 Clutch (with Output
Carrier Shaft and Dampener)
Hub Assembly (58)

Inspect the hub assembly (475), dampener (476), and
apply plate (477) for wear or damage.

Output Carrier Assembly (68)

Inspect for damaged or stripped internal splines on the
output carrier assembly.

Checks

Causes

4-5-6 (with Turbine Shaft)
Clutch Assembly (56)

Inspect for damaged or worn clutch plates (433-435).

Inspect for damaged piston (439), piston dam (437),
dam retaining ring (436), and clutch spring (438).

Inspect for improper selective 4-5-6 clutch backing
plate retaining ring (431).

Inspect for cut, worn, or damaged turbine shaft fluid
seal rings (442).

Checks

Causes

Torque Converter Assembly (1) Diagnose torque converter for possible internal damage.
Fluid Pump Cover Assembly
(219)

Inspect for worn, damaged, or sticking converter feed
limit valve (220) and spring (221).

Inspect for worn, damaged, or sticking TCC control
valve (227) and spring (226).

Inspect for damaged stator shaft.

Control Valve Lower Body
Assembly (307)

Inspect for worn, damaged, or sticking torque converter
clutch (TCC) regulator apply valve (355).

4-5-6 (with Turbine Shaft)
Clutch Assembly (56)

Inspect for damaged turbine shaft.

Inspect for damaged turbine shaft O-ring seal.

2008 Chevrolet Silverado 1500

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

Sierra & Silverado