Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 38)

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Service Codes
4 Flashing Lights or CHECK TIRES Flashing (Codes 44, 45)
Type: Tire Leak (Imbalance)
Note: RUN FLAT overrides this fault.
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
An “Imbalance” code indicates that either the tire pressure on
one tire or wheel end was read lower than the other tires, or
there is an air leak someplace in the system.
Low tire pressure can be caused by a damaged tire, plugged
wheel valve filter or leaking air lines. An air leak can be located
either before or after the wheel valve.
Note: When using a diagnostic tool to inflate or inflate-hold a
channel with one low tire, air may be heard leaking out
or the Quick Release Valves (QRV) by the higher pres-
sure tires. This is normal and should stop once the low
tire is inflated to the pressure of the other tires.
The components located before the wheel valve that may
cause a “Tire Leak (Imbalance)” code include:
• Leaking wheel air seals
• Leaking control lines
• Restricted QRV exhaust port
Components located after the wheel valve that may cause an
imbalance include:
• Damaged tire
• Rim leaks
• Clogged or restricted Wheel Valve filter or valve stem
• Leaking air lines
• Wheel valve damage
To correctly diagnose the faulty component, connect the Diag-
nostic Tool (see "Diagnostics" for test equipment and descrip-
tions) and follow the procedure in the Tire Leak (Imbalance)
troubleshooting tree.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
Channel only
checks pressures. Tire pressure lower on one
tire than others. • Minor tire leakage at startup (leaked overnight)
• Severe tire damage or leaks
• Contaminated wheel valve filters
• Restricted tires valve stem
• Leaking lines
• Leaking seals
• Leaking wheel valve
• Crimped or restricted control lines