Spicer TPCS Troubleshooting Guide - Manual (Page 60)

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Service Procedures
Pneumatic Control Unit - Cleaning and Inspection
The following describes the procedure for disassembly,
cleaning, and inspection of the Spicer Tire Pressure Control
System Pneumatic Control Unit (P/N 673336, and 673316).
Components requiring replacement can be found in the
Illustrated Parts List (AXIP-0010).
Do not use cleaning solvents which are not compatible with
elastomer or rubber components. Use of Brake Cleaners, or
solvents containing Xylene or Methyl Ketone, is not
recommended.
1. Remove unit from the vehicle (refer to Service
Manual AXSM-0010).
2. Remove bottom cover plate screws (10e), cover
plate (10a), and gasket (10b). If the unit has a trailer
module, remove screws (10e), plate (10c), and
gasket (10d).
3. All cartridges (8) are normally open units with the
exception of the supply channel (9) which is nor-
mally closed. Ensure the normally closed cartridge
(9) is reinstalled in the supply port following clean-
ing. The cartridges can be removed by pulling them
from the bottom of the PCU.
4. If the unit is a 3-channel system, remove 6 solenoid
cover screws (3c) and 4 trailer module cover screws
(7c).
5. Lift solenoid cover and trailer module cover together
to clear solenoids.
6. Remove solenoids from operators by removing 9/16"
hex nuts on top of solenoids.
7. Remove solenoid operators from PCU body using a
1" wrench on the brass base (13).
Note: All operators with the exception of the deflate operator
are 3 way (indicated by threaded port in top of part). Do
not mix deflate operator or its internal plunger (15) with
other operators, or plungers (14). Ensure that both O-
rings (11,12) in operator bases are not lost.
8. Remove operator stem from base (13) on all opera-
tors using spanner wrench (16). If spanner wrench
is not available, double nutting the operator stem
(with the 9/16" hex nuts) will enable disassembly.
9. Inspect condition of poppets (14,15) inside operator.
Note: Deflate plunger (15) is specific to the deflate operator,
and is identified by its solid metal top. If poppets
appear in good condition, thoroughly clean poppet and
operator assembly. Verify the absence of any "sticky"
residue from oil contamination.
10. Reassemble each operator with the base. Do not
install assemblies on PCU body until it is completely
cleaned.
11. Spray cleaning solvent on cartridge bores within
PCU body to remove debris and oil residue. Thor-
oughly dry cartridge bores prior to further assembly.
12. Replacing cartridges is not typically required;
however, it may be desirable to replace the 3 outer
O-rings on each or any individual cartridge. These
are standard nitrile O-rings and the sizes are
provided on the following page. Replacement
cartridges are available if required. See Illustrated
Parts List (AXIP-0010).
13. Lightly lube cartridge O-rings with silicone grease
and install cartridges in body, verifying that the one
normally closed cartridge (9) is installed in the
Supply (IN) port.
Note: Excess lube on piston O-rings can block hole from sole-
noid to top of piston. Be careful only to wipe lube on
O-rings. Do not pack grooves.
14. Install base gasket (10b), base cover plate (10a), and
screws (10e). If 3-channel Pneumatic Control Unit,
install gasket (10d), plate (10c), and screws (10e).
Torque screws 40 to 45 in. lbs.
15. Verify presence of O-rings in bases of solenoid
operator assemblies and reinstall operators onto
Pneumatic Control Unitbody. Verify 2-way operator
(solid metal top) is in Deflate location. Specific
location of other operators (3-way) is not important.
16. Install solenoids on operators verifying proper
location per labels on solenoids and Pneumatic
Control Unit body.
17. Carefully tuck solenoid wires in area between
transducer and solenoids while reinstalling the
solenoid covers.
CAUTION