FSB 593-013

Field Service Bulletin
Trucks
Mack Trucks, Inc.
Greensboro, NC USA
Date
Group
No.
Release
Page
5.2014
593
013
01
1(13)
Grade Gripper Solenoid, Replacement
CHU, CXU, GU, TD
FSB 593-013, Grade Gripper Solenoid,
Replacement
(May 2014)
On some MACK CHU, CXU, GU, and TD truck models built between 04/31/2008 and 05/12/
2014, the solenoid valve for the grade gripper feature is prone to internal contamination in
harsh environments. The internal contamination of the solenoid valve is caused by the buildup of grime, salt, road debris and other solid contaminants. In some cases, the build-up of
solid contaminants caused the solenoid valve to malfunction. The malfunction causes the
trailer brake circuit to maintain trailer brake pressure after a grade gripper event.
Replacement of the existing solenoid valve, elbow, and the addition of a new vent will ensure
proper functionality of the grade gripper feature.
Note: This bulletin does not apply to MACK Trucks Australia.
W5090989
Required Parts
Grade Gripper Solenoid Replacement Parts
Item
Description
Part Number
Qty
1
Solenoid Valve
21396762
1
2
Elbow
3082873
1
3
Vent
25164397
1
PV729-FSB 593-013_M
USA65270
Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
Repair Procedure
You must read and understand the precautions and guidelines in Service Information,
group 5, “General Safety Practices, Brakes”” before performing this procedure. If you are
not properly trained and certified in this procedure, ask your supervisor for training before
you perform it.
DANGER
Do not attempt to repair or service this vehicle without having sufficient training, the correct
service literature and the proper tools. Failure to follow this could make the vehicle unsafe
and lead to serious personal injury or death.
1 Park vehicle on a flat and level surface.
2 Apply the parking brake.
3 Place the transmission in neutral or park.
4 Install the wheel chocks.
W7086748
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
5 Disconnect the cable from the battery’s negative terminal.
W3086747
6 If applicable, slide the fifth wheel to the rear most position to gain access to the solenoid
valve.
W9090990
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
7 Disconnect the harness from the solenoid.
W5090991
8 Disconnect the air lines shown.
Note: Note the position of the air lines before removal.
W5090993
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
9 Remove the solenoid valve assembly.
W5090994
10 Remove the fittings from the solenoid valve.
Note: Note the position of the fittings for installation.
W5090995
Page
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
11 Remove the elbow fitting from the solenoid valve.
Note: Note the position of the elbow fitting for installation.
W5090996
12 Position and clamp the solenoid in a vise by the valve body as shown.
W5090997
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
13 Remove the valve (1) from the solenoid valve (2).
Note: Note the position of the valve (1) for later installation.
CAUTION
Removal of the union fitting (3) from the solenoid valve (2) will cause damage to the
fitting.
Note: If the union fitting (3) is removed with the valve, clean and store both for installation.
Note: If the union fitting (3) is fixed in the solenoid valve after removal of the valve, discard
the solenoid valve and the union fitting, then clean and store the valve for installation.
W5090998
Page
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
14 Remove the existing solenoid from the vise.
15 Position and clamp the replacement solenoid in a vise by the valve body as shown.
CAUTION
To prevent damage to the solenoid valve, do not clamp the electrical portion of the
solenoid.
W5090999
16 Assemble the replacement solenoid valve (2), valve (1), and union fitting (3).
Note: Apply thread sealant to the fitting before assembly.
Note: if applicable, assemble a new union fitting (part number 25089731) and valve prior
to assembly with the solenoid valve.
W5091000
Page
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
17 Remove the replacement solenoid from the vise.
18 Install the replacement elbow fitting (part number 3082873) to the solenoid valve.
Note: Apply thread sealant to the solenoid before installing elbow fitting.
W5091001
19 Install the vent fitting (part number 25164397) on the elbow fitting.
Note: Ensure the inside and outside of the vent fitting is clean and free of any solid
contaminants before installation.
Note: Apply thread sealant to the vent fitting before assembly.
W5091002
Page
9(13)
Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
20 Install the solenoid valve fittings as shown.
Note: Apply thread sealant to the fitting before assembly.
W5090995
21 Position the solenoid valve assembly.
22 Install the fasteners securing the solenoid valve assembly.
23 Tighten the fasteners to 24 ± 4 Nm (18 ± 3 ft-lb).
W5091003
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
24 Connect the air lines.
W5091004
25 Connect the harness.
W5091005
Page
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
26 If applicable, return the fifth wheel to it’s original position.
W9090990
27 Connect the battery cable to the negative (ground) terminal.
W3086758
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Mack Trucks, Inc.
Field Service Bulletin
Date
5.2014
Group
No.
Release
593
013
01
28 Remove the wheel chocks.
W7086759
Reimbursement
This repair may be eligible for reimbursement
if a product failure was experienced within
time and mileage limits of the applicable
Warranty coverage. Reimbursement is
obtained via the normal claim handling
process.
UCHP
Reimbursement
eWarranty
Reimbursement
Claim Type (used only when uploading from
the Dealer Bus. Sys.)
01
01
Primary Labor Code
593-03-09-02
0.4 hrs.
5332E–01–80
0.4 hrs.
Causal Part
21396762
21396762
Labor Code
MACK Trucks North America reserves the right to make any changes in design or to make
additions to or upon its products without incurring any obligations to install the same on
vehicles previously built.
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