19 Va. Admin. Code § 30-70-460
B. Inspect for and reject if:
4. Breakaway braking devices are missing or inoperative or cable is frayed or broken, or trailers are not equipped with emergency breakaway brakes designed to:
d. Apply automatically when the pressure in the towing vehicle reservoir is reduced to a point between 45 and 20 PSI by a series of foot applications, when equipped with air brakes.
NOTE: A minimum of one wheel must be removed from each axle equipped with brakes to inspect the brake components.
Exceptions:
§ 46.2-1165 of the Code of Virginia.
Derived from VR545-01-07 § 46, eff. May 1, 1990; amended, Virginia Register Volume 10, Issue 8, eff. February 9, 1994; Volume 15, Issue 2, eff. November 11, 1998; Volume 21, Issue 4, eff. September 22, 2004; Volume 24, Issue 8, eff. March 1, 2008; Volume 28, Issue 24, eff. August 1, 2012; Volume 32, Issue 24, eff. October 3, 2016.