On-Board Diagnostic (OBD) System Software Upgrade (Reprogram Engine Control Module and Transmission Control Module as Required)

On-Board Diagnostic (OBD) system improvements have been identified for the vehicles listed in this bulletin. Revised calibrations that include these OBD system improvements should be installed as soon as practical.

Using A Tech 2 scan tool and TIS 2000, verify whether the calibration programmed into the vehicle’s ECM has been programmed with 12589519 or later. The GM Vehicle Inquiry System (GM VIS) may be checked to see if the vehicle's ECM has been programmed since 10/27/03 or the labor operation Y0007 has been claimed on the vehicle. If the 12589519 or later updated calibration has not been installed or the Y0007 labor operation has not been claimed, reprogram the ECM with the latest updated calibration from TIS 2000 version 11.25 for 2003 data update or later. Dealers should call Techline Customer Support Center (TCSC) if this update is not available.

In addition, vehicles with VINs from 45600415 to 45600569 should be checked in the GM Vehicle Inquiry System (GM VIS) to see if the Transmission Control Module (TCM) has ever been re-programmed. If the TCM has never been re-programmed, then the TCM should be reprogrammed with the latest updated calibration from TIS 2000 version 11.0 for 2003 data update or later.

Reprogram the Engine Control Module (ECM) and Transmission Control Module (TCM) on all affected vehicles, as identified above, including vehicles in new dealer inventory and any that return for service for any reason during the emission warranty coverage period.