Display: 5 Flashing Lights
System waits to check
Pneumatic Control Unit
Frozen water or other contaminant in transducer
pressure out of range when
Plugged PCU vent line
PCU s '"vented'
Poor ground connection to transducer
Faulty pressure transducer
Faulty Pneumatic 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 the tires for approximately
two seconds while monitoring the pressure.
An "Atmospheric" code is logged if the atmospheric
pressure reading is out of range. The atmospheric
pressure reading can be out of range as a result of a
blocked or restricted PCU or vent line, contaminated
pressure transducer (i.e., frozen water), air bleeding
back into the Pneumatic Control Unit (PCU) or because
of a faulty pressure transducer.
The components that can cause this code to be set
Faulty or contaminated pressure transducer
Faulty or contaminated Pneumatic Control Unit
Faulty Electronic Control Unit (ECU)
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
Atmospheric troubleshooting tree.
See "Troubleshooting Tips" on page 3-92.15 for general
guidelines on system diagnostics.
3-92.22 Change 3