Service Update for Inventory Vehicles Only-Transmission Control Module Reprogram (Low Speed Engine Braking Sensation Upon Automatic Downshift to First Gear) - Expires March 31, 2009

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

This bulletin provides a service procedure to reprogram the transmission control module (TCM) on certain 2008 Hummer H2 and H2 SUT vehicles equipped with a 6 Speed automatic transmission (RPO MYC). The new calibrations eliminate a low speed engine braking sensation upon automatic downshift to first gear that may be unpleasant to some customers.

This service procedure should be completed on involved vehicles currently in dealership inventory as soon as possible, but no later than March 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 (US), 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 Techline Tech 2® scan tool and TIS 2 Web with the calibration update. Use TIS 2 Web version 3.0 for 2008 (available on 3/03/08). TIS DVD subscribers will use TIS 2000 DVD version 3.0 for 2008 (to be shipped 3/17/08). If you cannot access the calibration, call the Techline Customer Support Center and it will be provided.

The "Required Field Actions" section of the GM Vehicle Inquiry System (GMVIS) must be checked to determine if a specific vehicle requires this action. If GMVIS indicates that Service Update Bulletin 08080 remains ‘open’ and TCM reprogramming has not taken place, reprogram the TCM using a Tech 2® scan tool with the calibration update from Techline Information System (TIS).

Notice: Before reprogramming, please check the battery condition to prevent a reprogramming error of any of the modules due to battery discharge. Battery voltage must be between 12 and 16 volts during reprogramming. If the vehicle battery is not fully charged, use an additional jump battery if necessary. Only use approved Midtronics charger or Jumper Packs, etc. to maintain proper battery voltage during programming. Be sure to turn off or disable any system that may put a load on the battery, such as automatic headlamps, daytime running lights, interior lights, heating, ventilation, and air conditioning (HVAC) system, radio, engine cooling fan, etc. A programming failure or control module damage may occur if battery voltage guidelines are not observed.

The ignition switch must be in the proper position. The Tech 2® prompts you to turn ON the ignition, with the engine OFF. DO NOT change the position of the ignition switch during the programming procedure, unless instructed to do so.

Make certain all tool connections are secure, including the following components and circuits:

DO NOT disturb the tool harnesses while programming. If an interruption occurs during the programming procedure, programming failure or control module damage may occur.

DO NOT turn OFF the ignition if the programming procedure is interrupted or unsuccessful. Ensure that all control module and DLC connections are secure and the TIS terminal operating software is up to date.

Tech 2 Pass-Thru Method

1. Verify the battery charge of 12 to 16 volts. The battery must be able to maintain a charge during programming. Use an additional jump battery if necessary. Only use approved Midtronics charger or Jumper Packs, etc. to maintain proper battery voltage during programming.
2. Connect the Tech 2® to the vehicle and the TIS terminal.
3. Turn the ignition to ON with the engine off.
4. After all warning chimes inside the vehicle have stopped, turn on the Tech 2.
5. On the TIS terminal go into SPS Programming.
6. In the top box Select Diagnostic Tool select Tech 2 Legacy Pass-Thru.
7. In the lower box Select Programming Process select Reprogram ECU.
8. Follow instructions on the TIS terminal. When you get to the Supported Controllers screen:

8.1.	In the top box select TCM, Transmission Control Module.

8.2.	In the lower box select Normal.

8.3.	Select NEXT.

9. Select NEXT when the calibrations screen displays.
10. Follow on screen prompts until programming is completed.
11. When programming is complete:

11.1.

Turn off Tech 2.

11.2.

Turn off ignition switch.

12. Wait 30 seconds.
13. Turn ignition switch to ON with engine off.
14. Turn on the Tech 2.
15. Go into diagnostics and check for DTC codes.
16. Clear all codes.

For vehicles repaired under this service update, use: