6.0L LY6, 4L80E MT1, G33903 G-Cutaway Rental Fleet Vans D4 and Reverse Gears Not Operating (Reprogram Both ECM and TCM)

Some customers may comment that the D4 and reverse gears in the transmission are not operating. Before the condition occurred, they may have observed that the speedometer reads zero intermittently while the vehicle is still moving, or they had been driving on certain specific mountainous terrain. This condition is only known to have occurred on model G33903 G-cutaway rental fleet vans produced with the following configuration:

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 ECM and 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. These calibrations will be available as an ECM/TCM programming sequence event.

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 both the engine control module (ECM) and 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. Select ECM Engine Control Module from the Supported Controllers screen.
5. Follow the on-screen instructions for programming the ECM.

5.1.	Module -- Select Engine Operation

5.2.	Select -- ECM P/N 12630562. Description: New calibration to ensure proper downhill mode operation

6. Using the MDI or Tech 2®, clear all DTCs if required.
7. Select TCM Transmission Control Module from the Supported Controllers screen.
8. Follow the on-screen instructions for programming TCM.

8.1.	Module -- Transmission

8.2.	Select -- TCM P/N 24251345. Description: New calibration to normalize first gear downshift.

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

For vehicles repaired under warranty, use: