Spicer TPCS Troubleshooting Guide - Manual (Page 32)

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Service Codes
Group: 1P! (Codes 11, 12, 13, 16, 22)
Type: No Deflate Signal
Code Description
Group 1P! indicates inadequate vacuum in the Pneumatic
Control Unit (PCU) prior to channel selection, or failure to
sustain a vacuum in the control lines following channel
selection. These codes will be set when the nominal vacuum
of 26" Hg drops to 17" Hg. Codes can be generated by one
channel, multiple channels or a combination of channels.
When a deflate is requested, the system first shuts off all the
channel control lines and generates a vacuum in the Pneu-
matic Control Unit alone. A failure to generate this vacuum
will result in Diagnostic Code 22.
Once the vacuum has been established in the Pneumatic
Control Unit, the individual channel control line(s) are opened
and a vacuum is routed to them. If a vacuum is not sustained
in the control lines, a 1P! fault is logged as follows:
11 - Front Channel
12 - Rear Channel
13 - Trailer Channel
16 - Individual channels OK but a combination of
channels results in low vacuum.
Note: If a vacuum loss occurs during an attempt to deflate
two or more channels at the same time, the system will
halt the deflate and re-attempt it one channel at a time.
This will result in a Code 16 being stored in the ECU.
Group1P! can be caused by:
• Line leak.
• Air seal or oil lip seal leaks.
• Plugged or restricted Pneumatic Control Unit vent
line.
• Faulty Pneumatic Control Unit.
To identify the root cause of the problem, connect the
diagnostic tool (see Diagnostic Section for test equipment
and descriptions) and follow the procedure in the 1P!
Troubleshooting Tree.
See "Troubleshooting Tips" for general guidelines on system
diagnostics.
System Mode Condition Possible Causes
(Listed in Likely Order of Occurrence)
Inflate Only Inadequate vacuum in the
Pneumatic Control Unit - Plugged or restricted Pneumatic Control Unit vent line.
- Faulty Pneumatic Control Unit.
Inflate Only No sustained vacuum in
control lines - Line leaks.
- Air seals, oil lip seals.