Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 26)

23
Service Codes
5 Flashing Lights or DDM – Dashes "--" (Code 32)
Type: Low Air Supply
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 the tires for approximately two seconds while
monitoring the pressure.
Code Description
A “Low Air Supply” code displays if system air pressure is
inadequate to perform a tire pressure check.
This occurs when the pressure switch will not close. The
components that can cause the pressure switch to remain
open include:
• Compressor governor cutout set too low
• Pressure switch unplugged
• Faulty pressure switch
• Faulty compressor
• Open or broken line from supply tank to Pneumatic
Control Unit (PCU)
• Crimped or plugged line from supply tank to PCU
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 Low Air Supply
troubleshooting tree.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
System waits to
check pressures Pressure switch won’t
close • Compressor governor cutout set too low
• Air dryer needs service
• Pressure switch unplugged
• Faulty pressure switch
• Faulty compressor
• Open or broken line from supply tank to PCU
• Crimped or plugged line from supply tank to PCU
Pressure Switch 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
A C
B A B
– or –
– or –