Chevrolet Silverado / GMC Sierra. Service manual — part 849

2. Remove the detent lever/IMS retaining bolt (1) using a T27 TORX® bit and discard the

retaining bolt.

3. Place a protective plate on the transmission case surface around the spherical pin (3).

Remove the spherical pin (3) from the transmission case.

4. Slide the manual shift shaft (5) through the detent lever/IMS assembly (4) and through the

manual shift shaft seal.

5. Rotate the detent lever/IMS assembly to disengage the park pawl apply assembly (2).

Remove the detent lever/IMS assembly (4).

Installation Procedure

material on the threads. Do not reuse the retaining bolt.

NOTE:

DO NOT mar the transmission case surface around the
spherical pin when removing or installing the spherical pin. An
unmarred surface is required to maintain the seal between the
control valve assembly and the transmission case.

NOTE:

DO NOT twist the spherical pin when removing the pin from the
transmission case. Damage to the transmission case can
occur.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 36: Detent Lever/IMS Retaining Bolt
Courtesy of GENERAL MOTORS CORP.

1. Place the new detent lever/IMS assembly (4) in position in the transmission case. Rotate the

detent lever/IMS assembly to engage the park pawl apply assembly (2). Reinstall the manual
shift shaft (5) through the manual shift shaft seal and through the detent lever/IMS assembly
(4).

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

2. Push the manual shift shaft (5) into the final position in the transmission case.

3. Install the spherical pin (3) into the transmission case that retains the manual shift shaft.

4. Install the detent lever/IMS retaining bolt (1) using a T27 TORX® bit.

Tighten: Tighten the bolt (1) to 10 N.m (92 lb in).

5. Install the control valve assembly. Refer to Control Valve Body Replacement.

6. Perform the FastLearn procedure. Refer to FastLearn Procedure.

TORQUE CONVERTER HOUSING BOLT SEAL REPLACEMENT

Removal Procedure

NOTE:

Refer to Fastener Notice .

IMPORTANT: The FastLearn, adapt, procedure must be performed. This

can be done in 1 step using a scan tool. If this procedure is
not done, the TCM adaptive values will be at the settings that
it learned for the old components and will be in slow
adaptive mode. Under these conditions, it will take an
unacceptably long time for the adaptive values to converge
to levels suitable for the new transmission.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 37: Torque Converter Housing Bolts
Courtesy of GENERAL MOTORS CORP.

1. Remove the torque converter from the transmission. Refer to Torque Converter

Replacement.

2. Remove any of the 10 bolts (1), bolt heads shaded, where leakage at the bolt head is

suspected.

IMPORTANT: The bolts (1) have a removable seal under the flanged head.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado