The official notice
Defect
On certain trucks, the air brake park control valve may develop either an internal air leak or an air restriction. With this condition, the park brake may not release or may release only partially. If a vehicle is on an uneven surface, the park brake may not hold the vehicle and could result in unintended vehicle movement. An unattended roll away vehicle could strike a bystander and/or cause property damage.
Safety Risk
No risk description available.
Remedy
Dealers will inspect and replace the external check valve on the air brake park control valve. If inspection determines the external check valve is damaged, the air brake park control valve will be replaced. Most vehicles will also require the replacement of an internal check valve in the air brake park control valve.