Spicer TPCS Troubleshooting Guide - Manual (Page 52)

49
Service Codes
Group: 12P! (Codes 61, 62, 63, 64, 65, 66)
Type: Wheel Valve Shut Off
Air Pressure Check
The Tire Pressure Control 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
Group 12P! code indicates that the system is unable to
confirm that tires on a given channel are able to sustain the
target pressure when the channel is depressurized. After any
change of pressure on a given channel, the Tire Pressure
Control System will return to that channel to confirm, or
"double-check" the new pressure before returning to the
periodic check interval. If the pressure is not the same, or
more than the last reading, the system will inflate again, and
then reconfirm that channel. After 7 - 10 confirmation
attempts, the system will log a 12P! code, and complete
operations on any remaining channel. The system will classify
the loss of air due to wheel valve closure as minor (codes 61,
62, and 63 on front, rear, and trailer respectively) or major
(codes 64, 65, and 66 on front, rear, and trailer respectively).
Note: Leaks from the tire(s) may be noted after the truck has
been idle overnight, as the tire(s) lose(s) air when the
truck is off and the system inoperative. By observing
the time required to achieve normal tire pressures after
starting the vehicle, many tire punctures can be
identified well before the tire incurs non-repairable
damage.
A confirmation failure can be caused by:
• Damaged or leaking tire(s).
• Leaking air line between the wheel valve and tire.
• Air passage restriction between the PCU and the
wheel valve.
• Wheel valve contamination or failure.
To identify the root cause of the problem, connect the
diagnostic tool (see Diagnostics Section for test equipment
and descriptions) and follow the procedure in the 10P!
Troubleshooting Tree.
See "Troubleshooting Tips" for general guidelines on system
diagnostics.
System Mode Condition Possible Causes
(Listed in Likely Order of Occurrence)
Normal Operation Loss of pressure during
shut off - Wheel Valve shut off failure.
- Air passage restriction.