Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 36)

33
Service Codes
5 Flashing Lights or DDM – Dashes "--" (Code 31)
Type: Pressure Switch
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
A “Pressure Switch” code displays if system air pressure is
inadequate to perform a tire pressure check, yet the pressure
switch status is “closed”.
This occurs when the pressure switch will not open. The com-
ponents that can cause the pressure switch to remain closed
include:
• Pressure switch wire shorted to ground.
• Faulty pressure switch (failed closed).
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 Pressure Switch
troubleshooting tree.
Note: This feature is only available on 2-channel systems.
This fault could be logged as a result of a single-
channel system (with a single-channel Pneumatic Con-
trol Unit [PCU]) being configured as a two-channel sys-
tem. See “Configuration Error” troubleshooting tree to
verify correct harness configuration selection.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
Pressure check
only Pressure switch shorted or
won’t open. • Pressure switch wire shorted to ground
• Faulty pressure switch (failed closed)
• Faulty PCU (leaks air during supply tank check)
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
– or –