NHTSA Complaint #10732120 — 2011 MERCEDES-BENZ ML350

WITH THE GEAR SELECTOR IN PARK AND THE PASSENGER SIDE FRONT SEAT OCCUPIED, THE VEHICLE ROLLED BACKWARDS FROM A 4.4 PERCENT GRADE AND OVERTURNED AS IT PROCEEDED DOWNHILL. INSPECTION OF THE TRANSMISSION PARKING GEAR REVEALED THAT THE PARKING PAWL HAD BEEN ACTIVATED BUT DID NOT ENGAGE A PARKING GEAR SLOT. THIS INCIDENT WAS ATTRIBUTED TO EXCESSIVE ANGLE ON THE PARKING GEAR SLOT SIDES, AN UNDERPOWERED PRESSURE SPRING IN THE PARK INTERLOCK MECHANISM, OR A COMBINATION OF BOTH OF THESE CONDITIONS. THESE CONDITIONS PERMITTED THE PARKING PAWL TO BE REJECTED FROM THE PARKING GEAR SLOTS AT SPEEDS WELL BELOW THE PARK PAWL ENGAGEMENT (TARGET) SPEED OF 6 KPH (3.7 MPH), AS DEFINED BY SAE SPECIFICATION J2208. A SERIES OF SUCH REJECTIONS WHILE THE DRIVERS SEAT IS UNOCCUPIED POSES A SAFETY HAZARD BY ALLOWING THE VEHICLE TO CONTINUE TO ROLL IN AN UNCONTROLLED MANNER ON CERTAIN SLOPES WHILE THE GEAR SELECTOR IS IN PARK. A MORE DETAILED ANALYSIS OF THIS ISSUE HAS BEEN PREPARED AND SHARED WITH MERCEDES-BENZ. PLEASE CONTACT ME TO OBTAIN THIS ANALYSIS AND THE RELATED RESPONSE FROM MERCEDES-BENZ REPRESENTATIVES.