DANA-AXTS0015
DANA SPICER CTIS (CENTRAL TIRE INFLATION SYSTEM)
TROUBLESHOOTING GUIDE
JULY 2010
DANA-AXTS0015 - Page 5 of 72
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General Information
CTIS Key Features
Component Description
Wheel Valve (WV)
All axles use a Wheel Valve (WV) at each end. Dual wheels are
typically connected to one WV to provide tire pressure
balance between duals. When the system is idle, the WV
isolates the tire(s). A standard tank valve is included for
manual inflation.
Quick Release Valve (QRV)
The Quick Release Valve (one per axle) receives pneumatic
signals from the Pneumatic Control Unit (PCU) and either
inflates the tires, or vents air from the tires causing them to
deflate. The QRV can be vented through the air stack to
provide for vehicle deep water fording.
Air Transport Valve (ATV)—Optional
The Air Transport Valve (ATV) may be added in-line between
the Wheel Valve and the tire. Its purpose is to manually lower
the tire pressure significantly, decreasing the height of the
vehicle, to allow the vehicle to be loaded onto planes, etc. with
low clearances.
Load Selection/Sensing—Optional
Some CTI systems make use of either a user selectable load
setting or an automatic load setting, which adjusts pressure
targets based on the load of the vehicle.
Electronic Control Unit (ECU)
The Electronic Control Unit (ECU) is the control center for the
entire Central Tire Inflation System. The ECU receives com-
mands from the driver through push buttons, and transmits
and monitors appropriate signals throughout the system.
Pneumatic Control Unit (PCU)
The Pneumatic Control Unit (PCU) is a solenoid controlled
manifold that controls the air system. It also contains the PCU
sensor (transducer) which reads tire pressures.
Speed Sensor or Speed Input
Speed is read from the vehicle data link or a separate speed
sensor.
Pressure Switch (PS)
The Pressure Switch (PS) acts as an electronic brake priority
switch. It prevents the Central Tire Inflation System from
using air from the supply tank until the brake system is fully
charged. The PS also ensures that enough pressure exists for
the system to operate properly.
Air Lines
The Central Tire Inflation System uses a dedicated pneumatic
system plumbed from the vehicles’ exiting supply tank. Air
lines between the Pneumatic Control Unit and the Quick
Release Valves (QRV) are called “Upper Control Lines”. Air
lines between the QRVs and the Wheel Valves are called
“Lower Control Lines”.
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