TM 9-2330-373-14 & P
1. Heed WARNING on page 4-64 and remove drain plug from bottom of relay valve by turning it counterclockwise.
2. Allow moisture to drain. Insert drain plug in position and turn clockwise to tighten.
1. With brake air system of semitrailer connected and charged, check if brakes apply properly.
2. Release brakes and check whether air pressure is being exhausted promptly.
3. With semitrailer brake system fully charged, close shutoff valve in emergency line tube on towing vehicle and
disconnect brake air hose coupling tagged EMERGENCY. Check whether semitrailer brakes apply automatically.
4. Connect brake air hose to coupling tagged EMERGENCY. Open shutoff valve on towing vehicle and check for
automatic semitrailer release of brakes.
1. With brake air system of semitrailer connected
LEAK TEST AREAS
and charged, apply soap and water solution to
cover flanges which hold diaphragms and to
brake air hose coupling tagged SERVICE. No
leakage should be present. If leaks are detected
tighten attaching hardware and tighten coupling
2. Coat exhaust port with soap and water solution.
Apply brakes and check for leaks.
3. Release brakes and apply soap and water
solution to exhaust port and check for leakage.
4. Disconnect EMERGENCY coupling (step 3,
operating test), coat exhaust port with soap and
water solution and check for leaks.