Service Update for Inventory Vehicles Only-Automatic Transmission Delayed Downshift-Reprogram Transmission Control Module-Expires August 31, 2009

THIS SERVICE UPDATE INVOLVES VEHICLES IN DEALER INVENTORY ONLY AND WILL EXPIRE AUGUST 31, 2009.

This bulletin provides a service procedure to reprogram the Transmission Control Module (TCM) on certain 2008-09 model year Pontiac G8 GT vehicles, equipped with 6.0L V8 (RPO L76 - VIN Y) engine and 6L80E six speed (RPO MYC) automatic transmission. Customers may experience a delay in acceleration or lack of performance from the automatic transmission when applying throttle at low speed, such as when exiting a corner. This may also be described by the customer as a flat spot or delayed shift and generally will be reported at approximately 20-25 MPH (30-40 kmh). Dealers are to reprogram the TCM with revised automatic transmission calibration.

This service procedure should be completed on involved vehicles currently in dealership inventory as soon as possible, but no later than August 31, 2009, at which time this bulletin will expire.

A list of involved vehicles currently in dealer inventory is available on the "Service Update Bulletin Information" link under the "Service" tab in DealerWorld (GM), or attached to the Dealer Communication (Canada) used to release this bulletin.

Important: Dealers are to confirm vehicle eligibility prior to beginning repairs by using the system(s) below. Not all vehicles within the above breakpoints may be involved.

Do not attempt to order the calibration number from GMSPO. The calibration numbers required for this service procedure are programmed into control modules via a Multiple Diagnostic Interface (MDI) or Tech 2® scan tool and TIS2WEB with the calibration update. Use TIS2WEB data version 8.0 for 2008 on or after 07/30/08 to obtain the calibration. If you cannot access the calibration, call the Techline Customer Support Center and it will be provided.

Service Programming System (SPS)

For step-by-step programming instructions, please refer to SI, the Techline Information System (TIS) terminal and Technical Service Bulletin 08-07-30-036.

Review the information below to ensure proper programming protocol.

Important: Verify that the 12-volt battery has a battery charge of 12 to 16 volts. The battery must be able to maintain a charge during programming. Only use approved Midtronics 165-PCS charger or equivalent to maintain proper battery voltage during programming. The J2534 MDI will reprogram the modules in less time than the Tech 2® scan tool.

Updated TCM calibrations are now available to address these concerns. Reprogram the controllers with the updated calibration files using the TIS2WEB Service Programming System (SPS) application.

1. Verify that there is a battery charge of 12 to 16 volts. The battery must be able to maintain a charge during programming. Only use approved Midtronics 165 PCS charger, a fully charged 12V jumper, or booster pack disconnected from the AC voltage supply to maintain proper battery voltage during programming.
2. Reprogram the transmission control module (TCM). Refer to SI and Service Programming System (SPS) documentation for programming instructions, if required.
3. Select J2534 MDI or Tech 2® Legacy Pass-Thru and Reprogram ECU from the Select Diagnostic Tool and Programming Process screen.
4. Using the MDI or Tech 2®, clear all DTCs if required.
5. Select TCM Transmission Control Module from the Supported Controllers screen.
6. Follow the on-screen instructions for programming TCM.

6.1.	Module - Transmission

6.2.	Select -- TCM. Description: New calibration to normalize first gear downshift.

7. Using the MDI or Tech 2®, clear all DTCs if required.

For vehicles repaired under this service update, use: