TM 9-2320-272-24-1
Table 2-7. CTIS Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 1. Inspect relief valve on pneumatic controller. If poppet is stuck out, replace relief valve
(para. 3-455).
Step 2. Determine if quick exhaust valve(s) is malfunctioning.
Refer to malfunction 1, test 4, steps 1 and 2.
Step 8. With CTIS at Hwy air pressure, turn battery switch to "OFF" position. Check for air
leaks from pneumatic controller. If air is leaking, replace or repair pneumatic controller
(para. 3-454).
Step 4. Inspect air lines between pneumatic controller, quick exhaust valves, and wheels for
leaks, cracks, damage, and restrictions.
Refer to malfunction 1, test 1, step 1.
Step 5. Perform leak test on hub air seals (para. 3-462). Replace faulty air seals
(para. 3-460 or 3-461).
Step 6. While operating CTIS, select a mode to cause deflation. As tire deflation occurs, a
small amount of air should escape from relief valve. If no air escapes from relief valve,
pneumatic controller is not functioning properly Replace or repair pneumatic controller
(para. 3-454).
Test 2. Determine if wheel valve(s) is closing properly.
WARNING
Air pressure in tire is released during step 1. Eyeshields must be
worn. Failure to do so may result in injury to personnel.
CAUTION
Do not inflate any tire on the M939A2, including the spare, unless
external air source is known to be as clean and dry as air supplied
by vehicle. If in doubt, use vehicle's air supply. Contaminated air
may disable the CTIS.
Step 1. Check for obstructed air flow between wheel valve and wheel.
a. Manually inflate any tire that does not deflate properly to 80 psi (552 kPa).
b. Disconnect hose assembly from wheel valve. Note consistency of air flow from hose
connected to wheel. If air flow varies, or is intermittent, sufficient water has collected
in tire to cause icing of air passage. (This can happen even at temperatures above
freezing.)
c. Repeatedly till tire with dry air and deflate until flow from hose connected to wheel
is consistent.
d. Connect hose assembly to wheel valve.
Step 2. Remove filter from wheel valve and replace filter if obstructed (refer to Chapter 2,
PMCS).
Step 3. Retest system by performing step 1. If not operational, replace wheel valve (para. 3-456
or 3-457).
END OF TESTING!
7. CONTROL PANEL LIGHTS WORK, SYSTEM FAILS TO INFLATE OR DEFLATE
Test 1. Determine adequacy of air supply to CTIS.
Refer to malfunction 1, test 1, steps 1 and 2.
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