Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 42)

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Service Codes
2 Terrain Lights on Solid or DDM – Dashes "--" (Codes 23, 24)
Type: Between Modes
Code Description
A “Between Modes” occurs if a channel inflates or deflates too
slowly. The maximum allotted time for an inflate is 40 min-
utes, or 20 minutes for a deflate. The most likely cause for a
slow inflate is a faulty compressor or similar problem result-
ing in inadequate air supply to the Central Tire Inflation Sys-
tem. The most likely cause for a slow deflate is a leaking
upper control line, causing the deflate signal to be low.
If the system is able to generate a sufficient air supply, a
“Between Modes” code means that a leak or restriction exists
in an air passage. The components that may contain a
restricted or leaking air passage include:
• Wheel valve air filters
• Quick Release Valve (QRV)
• Pneumatic Control Unit (PCU) vent port restriction
• Air supply lines
• Restricted tire valve stem
• Faulty PCU relief valve
• Restricted QRV exhaust
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 Between Modes
troubleshooting tree.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
Pressure check
only Slow inflate • Faulty compressor
• Restricted flow at wheel valve air filters
• Crimped or plugged lines
Pressure check
only Slow deflate • Restricted flow at wheel valve air filters or valve stem
• Leaking upper control lines
• Plugged or restricted PCU vent port
• Restricted tire valve stem
• Faulty PCU relief valve
• Restricted QRV exhaust port