2011 Chevrolet Silverado U0073 Fault Code: Transmission Not Shifting Out of Park After TECM Software Upgrade
I recently encountered the U0073 fault code on my 2011 Chevrolet Silverado during a software update from an old TECM to a new TECM. The vehicle started successfully after installation and all systems initially functioned normally. However, it now fails to shift out of park—stuck in park despite the engine running. The U0073 code indicates no communication or serial data on the transmission control bus, which typically results in the transmission defaulting to park. I'm trying to determine what could have caused this issue after the TECM software update. Is it possible that the new TECM firmware failed to properly initialize the transmission communication? Any insights into potential causes or troubleshooting steps would be greatly appreciated.
Are there any other diagnostic trouble codes present? U0073 specifically indicates a lack of serial bus data between the TECM and transmission, which may suggest communication failure. Does the TECM (Transmission Electronic Control Module) properly register in your system? If not, this could point to a hardware or wiring issue. Could you confirm whether this is a 6.0L V8 engine or another variant—engine type might influence how the TECM interacts with transmission control?