Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 44)

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Service Codes
2 Terrain Lights on Solid or DDM – Dashes "--" (Codes 11, 12, 16)
Type: Deflate Signal
Code Description
A "Deflate Signal" indicates inadequate deflate signal in the
Pneumatic Control Unit (PCU) or failure to sustain the signal
in the control lines of a given channel.
When a deflate is requested, the system drops the control line
pressure to a preset level which is established by the PCU’s
relief valve. 2-channel systems may start separate channels at
different times.
If the proper pressure (vehicle specific, but typically a subset
of 6-22 psi) cannot be maintained by the PCU, either a Chan-
nel Deflate Loss or Loss of Deflate signal code is logged.
On 2-channel systems, if the relief valve pressure (deflate sig-
nal) cannot be maintained while both channels are deflating,
the system will attempt to deflate the channels individually
and will log “Deflate Signal” codes for an individual channel
with a problem.
This can be caused by:
• Faulty PCU (relief valve)
• Plugged or restricted PCU vent line
• Line leak
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 Deflate Signal
troubleshooting tree.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
Inflate only Inadequate deflate signal in
the PCU and control lines • Plugged or restricted PCU vent line
• Faulty PCU relief valve
• Faulty PCU
• Poor ground connector to PCU sensor
• Faulty PCU sensor
PCU Sensor Harness Connector
T S
A B
C
U
R
P
a
b
c
V
D
E
F
G
W
H
X
J
K
Y L
M Z
N
ECU Harness Connector
A B C D E
A B C D E
A B C D E
F G H J K 3
2
1
F G H J K
F G H J K
C A B
A B
C
– or –
– or –