Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 34)

31
Service Codes
5 Flashing Lights or DDM – Dashes "--" (Codes 33, 34)
Type: PCU Sensor
Code Description
A "Pneumatic Control Unit (PCU) Sensor" code occurs when
the Electronic Control Unit (ECU) receives an unusually high
or low reading from the PCU sensor. A diagnostic tool will
specify which of the two conditions is responsible for setting
the code.
Initial troubleshooting steps involve checking for a shorted-
to-ground or an open PCU sensor circuit.
If the circuits check out OK, secondary causes could involve a
faulty sensor or a faulty ECU.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
No operation No PCU sensor reading • Sensor electrically disconnected
• Pressure signal wire open
• Pressure signal wire shorted to ground
• PCU sensor VREF wire open
• PCU sensor VREF wire shorted to ground
• PCU sensor ground wire open
• Faulty sensor
• Faulty ECU
No operation High PCU sensor reading • Pressure signal wire shorted to VBAT or VREF
• Faulty sensor
• Faulty ECU
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 –