Check for a faulty air brake valve.

Refer to Air Brake Application Valve Operational Check .

Check the air line for leaks.

Refer to Air Brake System Leak Test .

Check the compressor or the governor for leaking.

Refer to Air Compressor Governor Valve Diagnosis .

Check the single check valve for leakage.

Refer to Reservoir Check Valve Operational Check .

Check the spring brake chamber hose for leakage.

Refer to Air Brake System Leak Test .

Check the spring brake chamber diaphragm for leakage.

Refer to Air Brake System Leak Test .

Check if the reservoir drain valve is open or is leaking.

Refer to Air Brake Reservoirs Contain Water .