Defect
Certain vehicles equipped with optional Wabco air dryer do not comply with the requirements of CMVSS 121 - Air Brake Systems. Vehicles were built with the check valves incorrectly positioned between the supply tank and the secondary air reservoir, such that a loss of reservoir pressure is possible in the event of a leak in the system.
Safety Risk
No risk description available.
Remedy
Air line plumbing will be revised to incorporate check valving to provide air reservoir isolation.