FIELD SERVICE CAMPAIGN – 24213
04 August 2025
SUBJECT:
Hill Hold Assist Installation
MODELS INVOLVED:
IC Bus™ Electric CE Series school bus
DEFECT DESCRIPTION:
Certain IC Bus™ Electric CE Series school buses may need the installation of the Hill
Hold Assist components.
SUBJECT DESCRIPTION:
Installing Hill Hold Assist (HHA) feature onto the vehicle using the installation kit. This kit
includes pneumatic lines, fittings, valves, electrical terminated harnesses, and a switch.
The pneumatic lines and fittings will be used to connect to the HHA valve assembly
from the air tank, rear valve, and foot valve. The HHA valve assembly will be controlled
with a switch. The electrical harnesses will be installed to the HHA solenoid valve,
through the chassis harness, and to the Antilock Brake System (ABS) module. Refer to
the most current IC Bus™ Electric CE Series Operation and Maintenance Manual for
more details.
ELIGIBILITY:
This procedure applies ONLY to vehicles marked in the International® Service PortalSM
with FSC 24213. Also complete any other open campaigns listed on the Service Portal
at this time.
TOOLS REQUIRED:
Description
Audio Unit Removal Tool
Battery Charger 55 amp
EZ-Tech® or EST with Service Diagnostics
Solutions (SDS) Software
Table 1 Tool Information

Tool Number
ZTSE4715
PSC550CC

Quantity
1
1

N/A

1

PARTS REQUIRED:
NOTE: See parts catalog for BOM if individual parts are needed.
Part Number

Description

Quantity

8000989C91

KIT, PART, HILL HOLD ASSIST
INSTALLATION

1

3578733C1

LIGHT, INDICATOR, LED ON (GREEN)

1

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Page 1

Part Number

3533928C1

Description

LIGHT, INDICATOR, LED BACKLIGHT
(AMBER)

ANTILOCK BRAKE SYSTEM (ABS) CONTROL
8000988C91
MODULE, UNPROGRAMMED
Table 2 Parts Information

Quantity

1
1 (If Needed)
See iKNow
Article link in
Step 6

WORK INSTRUCTIONS
WARNING! To prevent personal injury or death, wear and use approved highvoltage Personal Protective Equipment (PPE) when near a high-voltage electric
vehicle. Inspect PPE before use. Do not use gloves or other PPE with expired
dates, holes, cracks or damage. NEVER touch energized ORANGE high-voltage
cables or high-voltage components without wearing approved high-voltage PPE.
WARNING! To prevent personal injury or death, or damage to property, NEVER
service a high-voltage vehicle without completing High-Voltage Safety training.
Before working on vehicle, read and obey all High-Voltage Safety and Lock-Out
Tag-Out procedures and information.
WARNING! To prevent personal injury or death, or damage to property, read all
information in the Safety Information and High-Voltage Safety sections of the
service manual.
WARNING! To prevent personal injury and / or death, or damage to property, park
vehicle on hard flat surface, turn the engine off, set the parking brake, and install
wheel chocks to prevent the vehicle from moving in both directions.
WARNING! To prevent personal injury and / or death, always wear safe eye
protection when performing vehicle maintenance.
WARNING! To prevent personal injury and / or death, or damage to property, if
the vehicle must be raised, do not work under the vehicle supported only by
jacks. Jacks can slip or fall over.
WARNING! To prevent personal injury and / or death, or damage to property, keep
flames or sparks away from vehicle and do not smoke while servicing the
vehicle’s batteries. Batteries expel explosive gases.

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Page 2

1. Park vehicle on a dry and level surface.
2. Put drive mode selector in Neutral and set parking brake.
3. Release air pressure from vehicle air tanks. Refer to appropriate service manual for
detailed instructions.
4. Turn ignition to Key OFF position.
5. Install wheel chocks.
NOTE: The ABS module has a special order process and the VIN must be
provided when ordering as a critical order.
6. Using the iKNow article IK0400171, determine the status of the VIN:
IK0400171
a. If VIN is on the list, order ABS module for Step 80. Continue to Step 7.
b. If VIN is not on the list, do not order ABS module. Continue to Step 7.
7. Turn 12V disconnect switch OFF. Refer to appropriate technician manual for
instructions.
8. Perform High-Voltage Isolation Level 2. Refer to appropriate technician manual for
instructions.
9. Unlatch and open hood.

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Page 3

Figure 1. Air Dryer Location
1. Outboard side of high-voltage air compressor box
2. Air dryer
10. Keep vehicle lifted to gain access to air dryer (Figure 1, Item 2).

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Page 4

Figure 2. Mounting Hole Locations (Outside of the Box)
1. Bottom edge to center of 1/4 in (6.35 mm) discharge line bracket hole: 2 3/8 in
(60 mm)
2. Outboard side of high-voltage air compressor box
3. Right edge of box to center of discharge line bracket hole: 10 in (254 mm)
4. Right edge of box to center of 0.7 in (16 mm) mounting hole: 15 in (26 mm)
5. Discharge line bracket hole
6. Top edge of box to center of 0.7 in (16 mm) alignment tab hole: 0.9 in (22 mm)
7. Alignment tap hole
8. Mounting bolt hole
9. Bottom edge of box to center of 0.6 in (16 mm) mounting hole: 1 in (26 mm)
11. Using a light-colored paint marker, mark mounting hole locations (Figure 2, Items 5,
7 and 8) on outboard side of high-voltage air compressor box (Figure 2, Item 2)
next to air dryer.
12. Install 5/8 in (16 mm) diameter drill bit into drill.
13. Drill one hole on the side of high-voltage air compressor box for HHA valve
assembly support bracket using measurements (Figure 2, Items 4 and 9).
14. Drill one alignment hole on the side of high-voltage air compressor box for
alignment tab using measurements (Figure 2, Items 4 and 6).
15. Install 1/4 in (6.35 mm) diameter drill bit into drill.
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Page 5

16. Drill one hole on the side of high-voltage air compressor box for discharge line
support bracket using measurements (Figure 2, Items 3 and 5).
17. Debur drilled holes on the side of high-voltage air compressor box.

Figure 3. Hill Hold Assist (HHA) Solenoid Valve Assembly
1. Bracket
2. HHA solenoid valve
3. Brass elbow fitting (2)
4. Pipe union
5. Release valve
6. Bolt, washer, and nut (2)
7. Composite elbow fitting
8. Pipe coupling
9. RV-3 pressure reducing valve
10. Composite elbow fitting
18. Install HHA solenoid valve (Figure 3, Item 2) onto HHA valve assembly bracket
(Figure 3, Item 1).
19. Torque nut to 117 lb-in (13 N∙m).
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Page 6

Figure 4. Quick Release Valve (QRV) and Double Check Valve (DCV) Assembly
1. Brass plug fitting
2. QRV
3. Composite elbow fitting
4. Bracket stud (2)
5. Bolt, nut, and washer (1)
6. Composite elbow fitting
7. DCV
8. Composite elbow fitting
9. Composite elbow fitting
10. Composite elbow fitting
20. Install QRV (Figure 4, Item 2) onto HHA valve assembly bracket studs (Figure 4,
Item 4).
21. Torque nut to 117 lb-in (13 N∙m).
22. Install DCV (Figure 4, Item 7) onto HHA valve assembly bracket.
23. Torque nut to 117 lb-in (13 N∙m).

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Page 7

NOTE: All the composite fittings can swivel into the appropriate position after
torqued to specification
24. Install pipe coupling (Figure 3, Item 8) onto bottom of HHA solenoid valve (Figure 3,
Item 2).
25. Install RV-3 pressure reducing valve (Figure 3, Item 9) onto pipe coupling (Figure 3,
Item 8).
26. Position RV-3 pressure reducing valve to be perpendicular to HHA valve assembly
bracket (Figure 3, Item 1).
27. Install control port brass elbow fitting (Figure 3, Item 3) to top of the HHA solenoid
valve exhaust port.
28. Install pipe union (Figure 3, Item 4) to control port brass elbow fitting (Figure 3, Item
3).
29. Install control port brass elbow fitting (Figure 3, Item 3) to pipe union.
30. Position elbow brass fitting downward.
31. Install release valve (Figure 3, Item 5).
32. Install composite elbow fitting (Figure 3, Item 7) into control port of HHA solenoid
valve (Figure 3, Item 2).
33. Install composite elbow fitting (Figure 3, Item 10) onto supply port of RV-3 pressure
reducing valve (Figure 3, Item 9).
34. Install brass plug fitting (Figure 4, Item 1) to quick release valve delivery port
(Figure 13, Item 4).
35. Install composite elbow fitting (Figure 4, Item 9) to remaining quick release valve
delivery port.
36. Install composite elbow fitting (Figure 4, Item 3) to quick release valve supply port.
37. Install three elbow fittings (Figure 4, Items 6, 8, and 10) to double check valve.

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Page 8

Figure 5. Air Compressor Discharge Hose
1.
2.
3.
4.

Air compressor discharge hose
P-clamp
Hose support bracket
Bolt and nut assembly (2)

38. Remove bolt and nut assembly (Figure 5, Item 4) on P-clamp (Figure 5, Item 2) and
high-voltage air compressor box.
39. Remove hose support bracket (Figure 5, Item 3).
40. Remove and discard P-clamp.

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Page 9

Figure 6. HHA Valve Assembly Location
1.
2.
3.
4.

High-voltage air compressor box
HHA valve assembly bracket
HHA valve assembly
HHA valve assembly bracket mounting bolt and nut (not shown)

41. Install HHA valve assembly (Figure 6, Item 3) to side of high-voltage air compressor
box (Figure 6, Item 1).
42. Torque HHA valve assembly mounting nut (Figure 6, Item 4) to 195–240 lb-ft (265–
325 N∙m).

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Page 10

Figure 7. Air Compressor Discharge Hose

1.
2.
3.
4.

Hose support bracket
Bolt and nut assembly (2)
P-clamp
Air compressor discharge hose

43. Using bolt and nut assembly (Figure 7, Item 2), install hose support bracket (Figure
7, Item 1) to high-voltage air compressor box.
44. Torque bolt and nut assembly to 90 lb-in (10 N∙m).
45. Position air compressor discharge hose (Figure 7, Item 4) onto P-clamp (Figure 7,
Item 3) inboard of frame.
46. Install new P-clamp (Figure 7, Item 3).
47. Torque bolt and nut assembly to 90 lb-in (10 N∙m).

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Page 11

Figure 8. Air Tank Routing
1. Air tank fitting
48. Locate extra plug on primary air tank.
49. Remove the plug and install air tank fitting (Figure 8, Item 1) to air tank.

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Page 12

Figure 9. Air Tank Routing
1. New green air line
50. Install new GREEN air line (Figure 9, Item 1) to new brass fitting on primary air
tank.
51. Route new GREEN air line from the primary air tank fitting along driver-side frame
rail to the HHA valve assembly.

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Page 13

Figure 10. Air Line Routing at HHA Valve Assembly
1. New airline route and bend
2. Cable tie location (3)
3. Existing electrical and air line routing
52. Cut new air line to appropriate length and route to reach the air line fitting. Refer to
Figure 10 for appropriate routing and attachment points.

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Page 14

Figure 11. RV-3 Pressure Reducing Valve
1. Composite elbow fitting
2. RV-3 pressure reducing valve
3. New air line from air tank
53. Install air line (Figure 11, Item 3) into composite elbow fitting (Figure 11, Item 1) on
RV-3 pressure reducing valve (Figure 11, Item 2).

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Page 15

Figure 12. Compressor Air Hose
1. Air hose