TM 9-2320-260-20
Section V. COMPRESSED AIR AND AIR-HYDRAULIC
BRAKE SYSTEM TROUBLESHOOTING
2-13. GENERAL
a. This section provides troubleshooting information to diagnose and correct malfunctions which may
develop in the compressed air and air-hydraulic brake system for the M809 series vehicles covered in this
manual. Each symptom or malfunction given for an individual component or system is followed by a step(s)
that should be taken to determine the cause and corrective action that must be performed to remedy the
problem. The compressed air and air-hydraulic brake system is divided into the following functional
systems:
.
Parking Brake (page 2-90)
.
Air-Hydraulic Brake System (page 2-90)
.
Trailer Brakes (page 2-93)
.
Compressed Air System (page 2-93)
q Air-Operated Accessories (page 2-94)
interrelationship of these systems and should be used as a reference when performing compressed air and
air-hydraulic brake system troubleshooting.
Before taking any action to correct a possible malfunction, the following rules should be followed:
(1) Question operator to obtain information that might help determine the cause of the problem.
(2) Never overlook the chance that the problem could be of a simple nature. The problem could be
corrected with only a minor adjustment.
(3) Use all senses to observe and locate troubles.
(4) Use test instruments or gages to help determine and isolate problems.
(5) Always isolate system where malfunction occurs and then locate defective component.
(6) Use standard automotive theories and principles when troubleshooting vehicles covered in this
manual.
(7) Park vehicle on level surface and chock wheels before starting brake system troubleshooting.
c. Table 2-3 lists possible malfunctions that may occur in the vehicle or individual units of the vehicle.
This table covers troubleshooting procedures for the compressed air and air-hydraulic brake system only.
Troubleshooting procedures for the mechanical and electrical systems can be found in Chapter 2 of this
manual. Keep in mind that there may be minor differences between vehicles.
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