NHTSA ID Number: 11027209

Manufacturer Communication Number: SS 781-WST

TSB/Document Date: 2026-01-07


Summary

Revised Service Solution for Western Star vehicles with excessive water intrusion into the air system


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TSB/Document ID: SS 781-WST

Replacement Service Bulletin Number:

MFR Communication Date: 2025-12-09

MFR Internal Campaign ID/Software Version:

Communication Type: Other

NHTSA Components: SERVICE BRAKES

MFR Component System:

MFR Component Subsystem:


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Vehicles with excessive water intrusion into the air system.
For vehicles with 480-040 Wabco SS1200 dryer with excessive water intrusion
into the air system.
1. Ensure that the Pressure Controlled Check Valve (PCCV) is correctly
installed. REF: module-871 for the relevant install to the vehicle.

2. For vehicles with lower expected duty cycle of air system, replace
existing Wabco SS1200 dryer and add discharge line insulation per 131D70100.

DWG
INL
D00
TIE

-----COMPONENT ITEM-----BEN476263328
D12-34582-000
23-13476-000

-------ITEM DESCRIPTION---TUBE-RFLT SLV,1.25",HTSHD
INSTL-PP,DISCH,INSULATION,W
TIE-CLAMP,.5W,15L,4.13BUNDL

----QTY---2.000
R
4.000

UM
FT
EA
EA

S
C
A
P

3. For vehicles with higher expected duty cycle of air system, remove
existing Wabco SS1200 air dryer and related discharge line and replace
with either Wabco HP dryer or Bendix AD9si back-of-cab and route new
discharge line.
Example BOC air dryer spec: 480-C16780 – WABCO HP W/OC LHIB
DWG -----COMPONENT ITEM------ -------ITEM DESCRIPTION---- ----QTY---- UM S
D12-26761-002
DRYER(S) I/B LH BOC
R EA C
A00 D12-33694-000
INSTL-DRYER,WABCO,BOC,IB
R EA C
B00 D12-33698-000
INSTL-DRYER,WABCO,LHIB,BOC
R EA C
R00 D15-04741-059
DRLG-REF 8,2 HOLE
R EA C
R01 D15-04741-059
DRLG-REF 8,2 HOLE
R EA C
DRY WAB432 480 145 0P
DRYER-AIR,WABCO SS HP,W/OC
1.000 EA C
BK1 12-33228-000
BRKT-DRYER,IB-BOC
1.000 EA P
CMP 210502 000046
ELB-90,SAE 45D 12X08 MPT
1.000 EA C
WA1 23-09114-000
WASHER-HRDN,0.69X1.31X.177,
8.000 EA C

WA2
BL2
PLG
FIR
BL1
GOV
WET
NT1
064
006
BL2
NT1

23-09114-003
23-09440-150
23-13848-001
23-14137-001
23-14283-045
23-14396-002
23-14396-008
23-14451-116
48-25811-020
48-25855-030
49-00312-424
49-00312-555

WASHER-HRDN,0.53X1.06X.177,
SCREW-CAP,HEX,1/2-13,GR8PO
PLUG-PIPE,HOLLOW HEX,1/2
CABLE TIE-FIR TREE MOUNT,TY
BOLT-HEX,PC10.9,PO,M16X1.5X
ELB-90,1/4 PTC X 1/4 MPT
ELB-90,1/2 PTC X 1/2 MPT
NUT-HEX,LKG,VLH BLU,M16X1.5
TUBE-NYL 12,1/2",BLK,REINF
TUBE-NYL 12,1/4",SILVER
TRQ-BOLT,75NM,55FTLB,20PCT
TRQ-NUT,230NM,170FTLB,20PCT

3.000
3.000
1.000
1.000
4.000
1.000
1.000
4.000
20.000
20.000
R
R

EA
EA
EA
EA
EA
EA
EA
EA
FT
FT
EA
EA

C
C
P
C
P
P
P
P
C
P
P
P

Example discharge line spec: 131-C21733 – DISCHARGE LINE DD13 LHIB
DWG -----COMPONENT ITEM------ -------ITEM DESCRIPTION---- ----QTY---WB1 A12-28712-014
HOSE ASSY-WIREBRAID,#12,HIT
1.000
WB2 A12-28712-072
HOSE ASSY-WIREBRAID,#12,HIT
1.000
IRP A12-31498-000
TUBE-DISCH,LH BOC INRL PIPE
1.000
DPE A12-32298-000
TUBE-DISCH,DD13,MSAC,LHBOC
1.000
C00 D12-26024-001
INSTL-DISCH,LH I/B BOC W/ G
R

UM
EA
EA
EA
EA
EA

S
P
P
C
C
P

A00
B00
R00
BK1
BKE
WS3
CL2
TIE
CMP
BL2
BTE
CL1
BL3
TRE
NT3
INL
NT3
NTE
NT2

D12-28127-001
D12-32364-000
D15-04741-000
12-25463-000
12-30561-000
23-09114-000
23-09528-140
23-09796-309
23-12866-001
23-13345-020
23-13345-020
23-13824-000
23-14067-040
23-14137-000
23-14451-116
48-02159-094
49-00312-549
913023 008003
913023 008003

INSTL-DISCH,ENG,FPT,DD13
INST-PP,DISCH,DD13,LHBOC,ZDRLG-REF 8,1 HOLE
BRKT-R&C,INBD ZEE
BRKT-DISCH,43N,DD13,LHBOC
WASHER-HRDN,0.69X1.31X.177,
CLAMP-SUPPORT,.750 ID
CLAMP-CABLE TIE,1-3/4X8
ADPTR-1.06 45FTF TO M26 ORF
SCRW HEX FLNG,M8X1.25X20,
SCRW HEX FLNG,M8X1.25X20,
CLAMP-HOSE,CUSHIONED,.75ID,
BOLT-HEX,ZNAL,BK,M16X1.5X40
CABLE TIE ASSY-FIR TREE MOU
NUT-HEX,LKG,VLH BLU,M16X1.5
TUBE-RBR,INS,1 1/8IDX1/2WL
TRQ-NUT,200NM,148FTLB,20PCT
NUT-HEX FLG,M8X1.25,PRVL TR
NUT-HEX FLG,M8X1.25,PRVL TR

R
R
R
1.000
1.000
2.000
1.000
AR 25.000
1.000
1.000
3.000
1.000
1.000
AR 25.000
1.000
2.000
R
1.000
1.000

EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
FT
EA
EA
EA

P
C
P
P
C
C
P
C
C
P
P
P
P
C
P
C
P
C
C

1


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