Spicer CTIS (Central Tire Inflation System) Troubleshooting Guide - Manual (Page 25)

22
Service Codes
Low Pressure (Codes 26,
27)
Low Pressure (Codes 26, 27)
On 2-channel systems, use the diagnostic
tool to identify the faulty channel: front or rear.
Using the diagnostic tool, initiate inflate mode
for the faulty channel.
Is there
extreme audible
pressure loss?
Repair faulty components
and recheck system.
Verify that the pressure switch opens
when the supply tank is below 80 psi.
Note: Primary and secondary air brake
gauges do not reflect actual pressure in
the supply tank.
Does the
pressure switch
open?
Replace pressure switch and
recheck system.
Is there a restricted
line between the supply
tank and PCU?
Make repairs to faulty
components and recheck
system.
After a pressure
check, is the pressure
reading <5 psi?
Replace PCU sensor
and recheck system.
Check harness and PCU for open supply or
control solenoids. See Solenoid Fault flowchart.
Replace PCU and recheck system.
Note: While replacing the PCU, pay particular
attention to possible air line contamination (e.g.,
oil, water, particles) which may suggest further
air system maintenance needs.
Does fault
reoccur?
Complete
Replace ECU and recheck system.
Note: ECUs are not a typical cause of problems. If
an ECU is replaced, the system should be carefully
rechecked to make sure the problem has been
fixed and does not reoccur.
No
Yes
No
Yes
No
No
Yes
Yes
No
Yes