Spicer TPCS Troubleshooting Guide: Older Systems (ECU's w_Dual Connectors) - Manual (Page 20)

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Troubleshooting
Troubleshooting Tips
This checklist outlines some general hints and guide lines that will be
helpful in tracking down and correcting operating problems.
Operator Control Panel only displays one active code.
Only the most recent fault displays on the Operator Control
Panel. In troubleshooting, be alert for related faults. Use of a
Diagnostic tool offers the advantage of spotting multiple active
faults as well as retrieving historical faults.
A cleared code alone does not indicate a corrected
problem.
A code is set by a specific fault condition and can be cleared
by switching on the ignition. It’s possible to clear a code (i.e.,
remove it from the Operator Control Panel display) only to have it
display again when the fault condition re­occurs. To insure that
a prob lem is fixed, you must run the system through the same
operating modes that caused the problem and verify that the
fault code does not appear.
Disconnect both Electronic Control Unit connectors with
ignition off.
To avoid setting electrical fault codes, make sure that the
ignition is off before unplugging the wire harness connections
at the Elec tronic Control Unit module. Also, always disconnect
both the 30 way and the 18 way connectors, never just one.
Reconnect both connectors before switching on the ignition.
C Code faults are often connection problems.
The most likely cause of component faults will be damaged
wires or connections. As a first step in troubleshooting all C
codes, switch off vehicle ignition, then disconnect applicable
connectors and inspect for damage. (Switch ing off the ignition
is required before discon necting the harness at the Electronic
Control Unit, but is also a recommended practice before all
other electrical system disconnec tions.) Clean or repair all bad
connections before proceeding.
System is not continually pressurized.
When troubleshooting P Code faults, keep in mind that the air
system is only pressurized as needed (for example, in the inflate
mode). This means that such procedures as checking for leaks
require the system to be in an active, pressurized state.
Basic vehicle air and power systems are not covered in
this guide.
The Tire Pressure Control System requires air pressure and
electrical power supply from the base vehicle systems.
Diagnosis and service of these systems is outside the scope of
this manual.
Some faults will halt inflate or deflate sequences.
Upon sensing some fault codes, the Tire Pressure Control
System will immediately go to the “maintain” mode. This may
cause mode arrows to stop flashing before the system has
actually attained the pressures for the indicated mode.