Chevrolet Silverado / GMC Sierra. Service manual — part 868

Fig. 98: Placing 30 mm 12-Point Deep Socket Or Box-End Over Connector
Courtesy of GENERAL MOTORS CORP.

3. Place a 30 mm or 1 3/16 inch 12-point deep socket or box-end wrench (2) over the main

transmission connector (1).

4. Push inward on the socket or wrench to release the retaining feet that attach the connector

(1) to the transmission case.

5. Remove the wrench. Push inward on the electrical connector to separate from the

transmission case.

IMPORTANT: The main transmission connector is actually one end of the

internal wiring harness that protrudes through the
transmission case.

2008 Chevrolet Silverado 1500

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

Silverado

Fig. 99: Identifying Internal Wiring Harness Connectors
Courtesy of GENERAL MOTORS CORP.

6. Disconnect the internal wiring harness connectors (1) from the solenoids, the internal mode

switch (IMS), and from the transmission fluid pressure (TFP) switch.

7. Remove the solenoid retainers (2) for SS3 and SS2.

8. Remove the internal wiring harness from the transmission.

IMPORTANT: The solenoid retainers for shift solenoid 3 (SS3) and shift

solenoid 2 (SS2) also retain tabs on the wiring harness U-
channel. The solenoids will remain in position even after the
solenoid retainers are removed.

2008 Chevrolet Silverado 1500

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

Silverado

Installation Procedure

Fig. 100: Identifying Internal Wiring Harness Connectors
Courtesy of GENERAL MOTORS CORP.

1. Align the tabs on the new wiring harness (10) U-channel with the solenoid retainer slots for

SS3 (3) and SS2 (2) on the control valve assembly. Install the solenoid retainers (12) for the
SS3 (3) and SS2 (2) solenoids.

2008 Chevrolet Silverado 1500

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

Silverado

2. Attach the internal wiring harness (10) connectors to the solenoids, the IMS, and the TFP

switch.

Connector (8) goes to SS1 (5)

Connector (9) goes to the TFP switch (7)

Connector (11) goes to the MAIN MOD solenoid (19)

Connector (13) goes to the IMS

Connector (14) goes to the TCC PCS (1)

Connector (15) goes to SS2 (2)

Connector (16) goes to SS3 (3)

Connector (17) goes to PCS1 (4)

Connector (18) goes to PCS2 (6)

IMPORTANT: The internal wiring harness connectors should be in the

correct position for installation because of their pre-
assembled position in the U-channel.

2008 Chevrolet Silverado 1500

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

Silverado