Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 46)

43
Service Codes
No Terrain Lights or DDM – Dashes "--" (Codes 51, 52, 54, 55, 56)
Type: PCU Solenoid
(Supply, Deflate, Control, Front, or Rear)
Code Description
A “Solenoid Fault” code indicates an electrical fault in the
Pneumatic Control Unit (PCU). System operation is disabled
when these faults are detected.
The system shuts down in a fail-safe mode and turns off the
power to the solenoids.
The troubleshooting tree first tests internal solenoid circuitry.
Resistance outside the specified range of 30 to 80 ohms indi-
cates a defective solenoid. Succeeding steps check continuity
of the wire harness circuits between the PCU and the Elec-
tronic Control Unit (ECU). If the problem can be traced to a
faulty circuit or connector, make the necessary repairs. If the
troubleshooting routine leads to a problem with the solenoid
itself, the PCU must be repaired or replaced. If both the sole-
noid and the circuitry check out OK, the ECU is faulty.
See “Troubleshooting Tips” for general guidelines on system
diagnostics.
System Mode Condition Possible Causes (listed in order of likely occurrence)
No Operation PCU solenoid failed electri-
cal diagnostic test • Solenoid wire shorted to ground
• Solenoid wire shorted to power
• Faulty solenoid
• Faulty ECU
PCU Component Connector
ECU Harness Connector
PCU 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 –