TM 9-2320-363-20-1
Display: 5 Flashing Lights
Type: Pressure Read Low
System Mode
Condition
Possible Causes*
System waits to check
Faulty pneumatic system, or
Open line between Pneumatic Control Unit and wheel valve
pressures
extremely low pressure
Significant hub air seal leakage
reading
Open solenoid (PCU electrically or pneumatically
disconnected)
Crimped or plugged line between wet tank and Pneumatic
Control Unit
Faulty pressure transducer (ex frozen water)
Pneumatic Control Unit failure, supply or control off
Pressure switch failure, shorted closed
Faulty Electronic Control Unit
*Possible causes are listed In order of likely occurrence.
Air Pressure Check
Note that the Central Tire Inflation System is not
continuously pressurized; pressure checks occur on a
periodic basis. During tire pressure checks, the system
delivers
compressed
air
to
each
channel
for
approximately
two
seconds
while
monitoring
the
pressure in that channel.
Code Description
A "Pressure Read Low" code indicates an extremely low
pressure reading. The most likely cause is an open line
which would have a clearly audible leak during a
pressure check. A secondary cause could be a faulty air
delivery system (i.e., PCU electrically or pneumatically
disconnected).
Other components that can cause a Pressure Read Low
code are:
Electrically or pneumatically disconnected PCU
Faulty Pneumatic Control Unit (PCU)
Restricted line between the wet tank and
Pneumatic Control Unit
Faulty pressure transducer
Open line from Pneumatic Control Unit to Quick
Release Valve
Open line from Quick Release Valve to Wheel
Valve
To correctly diagnose the faulty component, connect the
Diagnostic Tool (see Page 3-92.16 for test equipment
and descriptions) and follow the procedure in the
Pressure Read Low troubleshooting tree.
See "Troubleshooting Tips" on page 3-92.15 for general
guidelines on system diagnostics.
3-92.18 Change 3