TM 5-3805-254-20-1
ORGANIZATIONAL TROUBLESHOOTING - CONTINUED
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
68.
REAR BRAKES DO NOT WORK - CONTINUED.
NOTE
Check AIR PRESSURE gage for air pressure between 90 and 130 psi. If specified air pressure is not
present, start engine and check that air pressure in air system is between 90 and 130 psi (TM 5-3805-254-
10). Shut down engine (TM 5-3805-25410).
Step 4.
Check rear relay valve (1) for input air pressure as follows: using 1 1/4-inch open-end wrench,
loosen input hose fitting (2) six turns. Have assistant press down brake pedal (3), listen for hissing
noise at input hose fitting (2), release brake pedal (3).
a. If hissing noise is heard at input hose fitting (2), rear relay valve (1) must be replaced.
Notify Direct Support Maintenance.
b. If hissing noise is not heard at input hose fitting (2), go to step 5.
Step 5.
Check front relay valve (4) for output air pressure as follows: using 1 1/4-inch open-end wrench,
loosen output hose fitting (5) six turns. Have assistant press down brake pedal (3), listen for hissing
noise at output hose fitting (5), release brake pedal (3).
a. If hissing noise is not heard at output hose fitting (5), replace front relay valve to rear
relay valve hose (6) (page 2-1101).
b. If hissing noise is heard at output hose fitting (5), tighten using 1 1/4-inch wrench, and
go to step 6.
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