NHTSA Complaint #11541633 — 2011 CHEVROLET SILVERADO 3500

The contact owns a 2011 Chevrolet Silverado 3500. The contact stated while driving approximately 10 MPH and slowing for a traffic signal, the vehicle downshifted very hard. The contact stated that there was an audible clunking sound while the transmission was downshifting. The contact stated that at approximately 1 MPH, the rear wheels locked up and the vehicle came to a sudden stop. The contact stated that the failure had recurred and was unpredictable. The contact stated that the "Shift Inhibited" message was displayed. The contact stated that the rough shifting occurred at various speeds while upshifting or downshifting. The contact had taken the vehicle to an independent mechanic where it was diagnosed and determined that the Transmission Control Module (TCM) needed to be replaced. The contact was informed that the TCM module was on a national back order. The vehicle had not been repaired. The manufacturer had not been informed of the failure. The failure mileage was approximately 220,000.