TM 5-3805-262-20
3-19. AIR BRAKE SYSTEM TROUBLESHOOTING (CONT)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
3. LOW AIR PRESSURE (AIR PRESS GAGE INDICATES IN RED ZONE AND LOW AIR PRESSURE
BUZZER SOUNDS) (Cont).
Step 12.
Step 13.
Step 14.
Step 15.
Step 16.
(Cont).
a . ( C o n t ) .
Reconnect parking brake valve hose to straight fitting.
Close air reservoir drain valve.
Go to step 13 below.
b. If air pressure is still low, go to step 14 below.
Start engine and operate at 1000 rpm.
Check parking brake valve hose connected between declutch treadle
and valve and parking brake valve for air leaks. Use soap solution
as necessary.
a. If air leaks seen, replace hose (page 7-74).
b. If air leaks not seen, troubleshoot parking brake system (page
3-112).
Start engine and operate at 1000 rpm.
Check hoses, lines and fittings between air reservoir and declutch
treadle and valve, and brake treadle and valve and declutch treadle
and valve for air leaks. Use soap solution as necessary.
a. If air leaks seen, replace parts as necessary (page 7-74).
b. If hoses okay, go to step 15 below.
With engine operating, apply soap solution around bottom bore of
treadle and valves.
Watch for air bubbles.
a. If bubbles seen, replace
treadle and valve (page
7 - 5 3 ) .
b. If bubbles not seen, go
to step 16 below.
T e l l a s s i s t a n t t o p r e s s t r e a d le
and valve down completely while
you apply soap solution on and
around bottom bore of treadle
and valve body.
Watch for air bubbles.
Repeat for other treadle and valve.
3-127
