Spicer TPCS Troubleshooting Guide - Manual (Page 30)

27
Service Codes
Group: 12C! (Codes 51, 52, 53, 54, 55, 56)
Type: PCU Solenoids
• Front (51)
• Rear (52)
• Trailer (53)
• Supply (54)
• Deflate (55)
• Control (56)
Code Description
Group 12C! indicates an electrical fault in the Pneumatic
Control Unit (PCU). Codes 51 through 56 specifically
designate which solenoid in the PCU is faulty. System
operation is disabled when this fault is detected.
The system shuts down in a fail-safe mode and turns off
power to the solenoids.
The troubleshooting tree first tests internal solenoid circuitry.
Resistance outside the specified range of 7 to 25 ohms
indicates a defective solenoid. Successive steps check
continuity of the wire harness circuits between the Pneumatic
Control Unit and the Electronic 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 Pneumatic Control Unit
must be repaired or replaced. If both the solenoid and the
circuitry check out, the Electronic Control Unit is faulty.
See "Troubleshooting Tips" for general guidelines on system
diagnostics.
System Mode Condition Possible Causes
(Listed in Likely Order of Occurrence)
No operation Pneumatic Control Unit
solenoid failed electrical
diagnostic test - Connector unplugged or faulty wiring.
- Solenoid wire open.
- Solenoid wire shorted to ground.
- Solenoid wire shorted to power.
- Faulty solenoid.
- Faulty Electronic Control Unit.
E
F
D
G
C
H
B A
K
ECU
Harness Connector
A B
G
3
2
1
A
A
B
B
C
C
C
D
D
D
E
E
E
F
F
F
G
G H J K
H
H
J
J
K
K
PCU Harness
Connector
A B C D E
K H G F
PCU Connector