Info - Changing Horsepower and/or Torque Rating - Policy and Procedures (GMC and Chevrolet Dealers)

Important: This service bulletin is not applicable to 'GM of Canada' dealers. Dealers in Canada should contact your Medium Duty District Service Manager.

This bulletin is intended to assist dealers in changing the horsepower (hp) and torque prior to delivery or after delivery to help better fit the customer's needs. If it becomes necessary to change the hp and torque rating on a Duramax™ 7800 (Isuzu 6HK1-TC) diesel engine, please follow the listed procedure in order to determine if the unit is capable of handling the increased hp and torque.

1. Review the appropriate model year Data Book to determine if the requested combination is available.
2. Call the Techline Customer Support Center (TCSC) at 1-800-828-6860 English or 1-800-503-3222 French to request a hp / torque change. The following will be needed by the TCSC:

•	A valid vehicle identification number (VIN)

•	A valid dealer code

3. The TCSC will perform the following steps during the request:

•	The TCSC will review engineering tables containing hp / torque compatibility with the vehicle transmission and driveline combination.

•	If verbally approved, the dealer will fax the HP Upgrade Dealer Request Form to the TCSC at (248) 265-9327.

•	The TCSC will create a Problem Tracking Record (PTR) used for tracking and billing.

•	The TCSC will update the "As Built" data file for future reference.

4. The TCSC will provide the following information to the dealer:

•	A Vehicle Configuration Index (VCI) Number (to be used to program the ECM via the Tech 2®)

•	A PTR number

•	A new hp / torque tag (to be adhered to the valve cover)

Important: The VCI number given is VIN specific and can only be used on that vehicle. Also, it is a federal regulation that the new hp / torque tag must be installed on the valve cover before the truck is released to the customer.

5. Listed in the data book is the cost of the upgrade with an additional charge of $100.00 (MSRP) for the TCSC support.
6. The PTR file will be transferred to the GM BARS group for billing to the dealers open account. A short description including the VIN and amount will be displayed on the invoice.

Important: Ensure that the engine control module (ECM) is installed in the vehicle and that the battery is fully charged before programming.

1. Turn ON the ignition with the engine OFF.
2. Turn OFF all accessories.
3. Connect the scan tool to the vehicle data link connector (DLC) and turn ON the scan tool.
4. Press Enter to go to the Main Menu.
5. Scroll down to Service Programing System at the Main Menu then press Enter.

Important: Select Request Info again if a VIN was previously stored in the scan tool.

6. Select Request Info then press Continue.
7. Enter the vehicle description by following the On-screen instructions then press Continue.

Important: Select No and write down the VIN if the VIN is incorrect.

8. Verify that the correct VIN is entered on the scan tool then press Yes.
9. Turn OFF the ignition.
10. Turn OFF the scan tool and disconnect it from the vehicle.

Important: The TIS supports service programming with the Tech 2 scan tool only.

11. Connect the scan tool to the TIS terminal. Power up the scan tool and then turn it ON.
12. Launch the TIS application at the terminal.
13. Click on Service Programming System at the main screen.
14. Select the following information on the Select Diagnostic Tool and Programming Process screen:

14.1.

Select Diagnostic Tool - Tech 2®.

14.2.

Select Programming Process - Reprogram ECU.

14.3.

Select ECU Location - Vehicle.

15. Verify that all connections are secure then click Next.
16. Click Next.

Important: You may receive a message stating that the control module could be a Service ECU if you selected NO to the VIN being correct. Click OK.

17. Verify that the VIN is correct then click Next.
18. Select PCM/VCM as the controller to be programmed.
19. Select VCI as the Programming Type then click OK.
20. Enter the VCI number given by the TCSC then click OK.
21. Verify your selection on the Calibration Selection screen then click Next.
22. Click next on the Summary screen.
23. TIS is now downloading the software and calibrations to the scan tool.
24. Click Close when the download has finished.
25. Turn OFF the scan tool.
26. Turn ON the ignition with the engine OFF.
27. Connect the scan tool to the DLC then turn it ON.
28. Press Enter to go to the Main Menu.
29. Scroll down to Service Programming System at the Main Menu then press Enter.
30. Select Program ECU.
31. Verify that the VIN is correct, and then press Continue.
32. Follow the On-screen instructions to program the ECM.

Important: There are NO learning procedures required for this ECM. All option content and fuel injector flow rate information previously stored in the ECM will remain unaffected. Consult the appropriate Service Information for further explanation.

33. Once the ECM is programmed, turn OFF the ignition and the scan tool.
34. Remove the original hp / torque tag from the valve cover and adhere the new tag reflecting the change.
35. Test drive the truck to ensure that there are no concerns.
36. The ECM hp / torque change is complete.

Important: If any concerns arise, please contact GMICT Technical Assistance at 1-800-MediumD (1-800-633-4863), prompt 3 or your DSPM.