NHTSA ID Number: 10200210
Manufacturer Communication Number: FSB 593 013
TSB/Document Date: 2021-08-09
Summary
On some MACK
CHU, CXU, GU, and TD truck models built between 04/31/2008 and 11/30/2015, 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 buildup of solid contaminants caused the solenoid valve to malfunction. A similar malfunction is possible if the solenoid valve is equipped with a vent fitting that freezes over. 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 tube fitting and tube will ensure proper functionality of the grade gripper feature.
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- Mixes well with conventional fluids
- Low-moisture formula provides excellent vapor lock...
- Ideal for hydraulic and disc brakes
- Provides an extra margin of safety in extreme braking...
- Mix of polyglycol ethers ensures hot brake-system operation...
- Excellent for ABS, disc and drum brake systems
- Delivers braking power when needed by avoiding a spongy...
- Both wet and dry boiling points exceed the minimum...
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TSB/Document ID: FSB 593 013
Replacement Service Bulletin Number:
MFR Communication Date: 2016-01-01
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ELECTRICAL SYSTEM: INTEGRATED TRAILER BRAKE CONTROL
MFR Component System:
MFR Component Subsystem:
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Field Service Bulletin
Trucks
Mack Trucks, Inc.
Greensboro, NC USA
This Field Service Bulletin replaces bulletin, “Grade Gripper Solenoid,
Replacement”, (USA70297) PV729-FSB593-013_M, dated (05.2015).
Date
Group
No.
Release
Page
1.2016
593
013
04
1(14)
Grade Gripper Solenoid, Replacement
CHU, CXU, GU, TD
FSB 593-013, Grade Gripper Solenoid,
Replacement
(January 2015)
On some MACK CHU, CXU, GU, and TD truck models built between 04/31/2008 and
11/30/2015, 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 buildup of
solid contaminants caused the solenoid valve to malfunction. A similar malfunction is possible
if the solenoid valve is equipped with a vent fitting that freezes over. 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 tube fitting and
tube will ensure proper functionality of the grade gripper feature.
Note: This bulletin does not apply to MACK Trucks Australia.
W5100449
Required Parts
Grade Gripper Solenoid Replacement Parts
Item
Description
Part Number
Qty
1
Solenoid Valve
21396762
1
2
Elbow
3082873
1
3
Tube Fitting
8397697
1
4
Tubing, Bulk
1113569
N/A
PV729-FSB593-013_M
USA74625
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
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
Page
2(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
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
Page
3(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
7 Verify whether or not the Grade Gripper solenoid is equipped with vent fitting (part number
25164397) as shown in the figure below.
Note: If the solenoid is equipped with a vent fitting, remove the vent fitting and proceed to
step 24 for elbow fitting and tube installation instructions only.
Note: If the solenoid is not equipped with a vent fitting, proceed to step 8 for Grade Gripper
Solenoid, Replacement instructions.
W5091002
8 Disconnect the harness from the solenoid.
W5090991
Page
4(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
9 Disconnect the air lines shown.
Note: Note the position of the air lines before removal.
W5090993
10 Remove the solenoid valve assembly.
W5090994
Page
5(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
11 Remove the fittings from the solenoid valve.
Note: Note the position of the fittings for installation.
W5090995
12 Remove the elbow fitting from the solenoid valve.
Note: Note the position of the elbow fitting for installation.
W5090996
Page
6(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
13 Position and clamp the solenoid in a vise by the valve body as shown.
W5090997
14 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
7(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
15 Remove the existing solenoid from the vise.
16 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
17 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
8(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
18 Remove the replacement solenoid from the vise.
19 Install the replacement elbow fitting (part number 3082873) to the solenoid valve.
Note: Apply thread sealant to the solenoid before installing elbow fitting.
W5091001
20 Install the solenoid valve fittings as shown.
Note: Apply thread sealant to the fitting before assembly.
W5090995
Page
9(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
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).
W5100451
24 Install the tube fitting (part number 8397697) on the elbow fitting.
Note: Ensure the inside and outside of the tube fitting is clean and free of any solid
contaminants before installation.
Note: Apply thread sealant to the tube fitting before assembly.
W5100450
Page
10(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
25 Cut approximately, 914 mm (36 in) of bulk tubing (part number 1113569).
26 Connect the 914 mm (36 in) section of bulk tubing to the tub fitting as shown in the figure
below.
W5100452
W5100452
27 Route the tubing from the tube fitting along the chassis harness and air line bundle. See
the figure below.
Note: The air line tubing must be routed inside chassis harness bundle.
Note: Use cable ties to secure the tubing to the chassis harness and air line bundle as
shown below.
W5100453
Page
11(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
28 Connect the remaining air lines.
W5100454
29 Connect the harness.
W5100455
W5100455
Page
12(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
30 If applicable, return the fifth wheel to it’s original position.
W9090990
31 Connect the battery cable to the negative (ground) terminal.
W3086758
Page
13(14)
Mack Trucks, Inc.
Field Service Bulletin
Date
1.2016
Group
No.
Release
593
013
04
32 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 (Grade Gripper Solenoid,
Replacement)
5939-03-09-02
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.
Page
14(14)
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