Spicer TPCS Troubleshooting Guide - Manual (Page 38)

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Service Codes
Group: 4P! (Codes 23, 24, 25)
Type: Channel Between Modes
Code Description
Group 4P! displays if any channel inflates or deflates too
slowly as shown below:
• 23 - Front Channel
• 24 - Rear Channel
• 25 - Trailer Channel
The maximum allotted time for each channel is 40 minutes for
an inflate, or 20 minutes for a deflate. The most likely cause is
a faulty compressor or similar problem resulting in
inadequate air supply to the Tire Pressure Control System.
If the system air supply is functioning properly, code group
4P! may indicate 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.
• Pneumatic Control Unit (PCU) vent port restriction.
• Air supply lines.
• Wheel valve exhaust port (deflate mode only).
To identify the root cause of the problem, connect the
diagnostic tool (see Diagnostics Section for test equipment
and descriptions) and follow the procedure in the
4P! Troubleshooting Tree.
See "Troubleshooting Tips" for general guidelines on system
diagnostics.
System Mode Condition Possible Causes
(Listed in Likely Order of Occurrence)
Pressure Check Only Slow Inflate - Faulty compressor.
- Restricted flow at wheel valve air filters or tire valve stems.
- Crimped or plugged lines.
Slow Deflate - Restricted flow at wheel valve air filters or tire valve stems.
- Plugged or restricted Pneumatic Control Unit vent port.
- Leaking lines.
- Plugged or restricted wheel valve exhaust port.