TM-9-2320-272-10

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; OPERATOR'S MANUAL

SEPTEMBER 2004
CHANGE 2

  TM-9-2320-272-10 - Page 369 of 481

TM 9-2320-272-10
3-20
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Table 3-1. Troubleshooting (Contd).
3-5. CTIS STATUS INDICATION AND MALFUNCTIONS
a. Central Tire Inflation System (CTIS).
CTIS is designed to work
automatically in case of tire leakage. Additionally, CTIS will adjust tire pressure
when a road surface selection is made, to preset valves. Refer to table 3-2, CTIS
Indications, for explanation of indications or malfunction.
b. CTIS Integration with the Airbrake System.
The Central Tire Inflation
System uses the same air compressor that supplies air to the vehicle brakes. The
vehicle brakes are always given priority over the CTIS. When brake operation
causes the air pressure in the brake reservoir to fall below a preset limit, inflation
will stop until the air compressor has refilled the brake reservoir. If the CTIS was
deflating the tires, it would continue to do so.
CAUTION
To prevent damage to transmission, refer to
paragraph 2-15 for proper transmission shifting
procedures.
c. Rapid Inflation.
The most rapid tire pressure increase is achieved during
vehicle operation. Keep the transmission downshifted to a lower gear. Keep engine
operation at 2,000 rpm. Engaging the turbocharger supplies extra air pressure
directly to the air compressor.
AIRBRAKE CONTROL KIT
53. TRAILER AIRBRAKES DO NOT OPERATE WHEN AIRBRAKE CONTROL HANDLE
IS PULLED DOWN.
Step 1. Check to see if trailer air supply valve control knob is not in pressed-
in position (para. 2-47).
If not, press in trailer air supply valve control knob and hold in place
for 15 seconds. Release valve. If valve does not stay in, notify unit
maintenance.
Step 2. Check to see if trailer air lines are securely connected to air
couplings of towing truck.
If not, securely connect trailer air lines of air coupling, and open air
coupling valves.


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