ISSUE DATE:
SERVICE BULLETIN SUBJECT:
VINs or MODELS AFFECTED:
COMPLETE BY:
SERVICE BULLETIN #:

9-30-2019
Hill Hold Solenoid Retrofit
Service Specified Buses
Next Service Opportunity
SC-19-124

NOTICE! It is expected that this process will require 3 hours per bus Please
schedule appropriately to minimize vehicle downtime.

HILL HOLD SOLENOID RETROFIT
This campaign updates the hill hold solenoid and associated components for improved performance.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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Tools/Supplies Required
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T-30 Torx Driver
Ratchet
10mm Socket
Calibrated Torque Wrench
Orange Torque Stripe Paint
Tubing Cutter
Allen Wrenches

Parts Required:
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048533
048541
000650
001162
048555
000623

PLATE, HILL HOLD, FRONT
FITTING, PTC, BRASS, 90 DEG, RIGID, 1/4 MPT X 3/8 PTC
FITTING, PTC, BRASS 1/4 MPT 3/8" OD TUBE
FITTING, PTC, COMPOSITE, 90 DEG, SWIVEL, 3/8 MPT"X 3/8 TUBE
SPACER, 0.17" ID (#8 SCREW), 5/16" OD, 1/4" LG, NYLON 6/6
TUBING, AIR, RED, 3/8 OD

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

1 EA
1 EA
2 EA
1 EA
3 EA
2 FT

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Procedure
1. Preform the Proterra approved Lockout/Tagout procedure to make the bus safe for work.
2. Working inside the Streetside rear compartment, open the three valves shown below to drain
the air tanks.

Open Valves

3. Remove any components from the Driver’s workplace necessary to access the lower ECAB
panel shown in the following photograph.

Remove Panel

4. Using a T-30 Torx Driver, remove the panel shown in the previous photograph.
5. Working inside the wheel well, disconnect the Air Lines circled in blue in the following
illustration. Also disconnect the harness connections for the Solenoid Valve and the Pressure
Transducer shown circled in red.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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6. Using a 10mm Ratchet/Socket, remove the three locknuts shown circled in green in the
previous illustration.
7. Remove the old Hill Hold Plate and the components that are attached to it.
8. Using the parts from the original Hill Hold Plate with the new parts included in the kit, build the
new Hill Hold Plate as shown in the illustration below. Three Spacers (048555) are used
underneath the Solenoid to space them above the Plate. All NPT fittings should have Loctite
567 applied to the threads before assembly.

9. Using a 10mm Ratchet/Socket, install the assembled Hill Hold Plate as shown in the illustration
below. Use the Locknuts that were remove earlier.

10. Using a Calibrated Torque Wrench with a 10mm Socket, torque the locknuts to 60 Inch
Pounds.
11. Mark the properly torqued fasteners with Orange Torque stripe Paint.
Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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12. Connect the air lines as shown in the illustration above. The tubing that was disconnected
earlier is shown properly connected with size callouts.
13. Connect the wiring harness to the Solenoid Valve and the Pressure Transducer.
14. Using a T-30 Torx Driver, reinstall the lower ECAB Panel.
15. Replace any other components that were removed to access the Hill Hold Plate.
16. Close the valves that were opened to drain the air tanks.

Close Valves

17. Remove the Lockout/Tagout devices and start the bus.
18. Allow the air pressure to build until the compressor stops.
19. Ensure that there are no air leaks before returning the bus to service.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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