7ISSUE DATE:
SERVICE BULLETIN SUBJECT:
VINs or MODELS AFFECTED:
COMPLETE BY:
SERVICE BULLETIN #:

6/1/2020
Traction Motor Inverter Enable Signal Retrofit
Service Specified Buses
Next Service Opportunity
SB-20-79

TRACTION MOTOR INVERTER ENABLE SIGNAL RETROFIT
NOTICE! It is expected that this process will require 4 hours per bus. Please
schedule appropriately to minimize vehicle downtime.

Retrofit Description:

This retrofit changes the traction motor inverter enable signal from 12 to 24 volts to improve reliability.

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/Parts Required
Tools and Supplies Required:
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•
•
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Wire Strippers
Side Cutting Pliers
Crimp Tool
Pin Extractor
Scissors
Heat Gun
Electrical Tape
Ratchet
13mm Socket
Calibrated Torque Wrench

Parts Required:
•

054221
RETROFIT KIT, FHT TM ENABLE 12V TO 24V (Consisting of)
o 001542
WIRE, #14 AWG, TYPE GXL, LIGHT GREEN, (LGN)
6 FT
o 001268
CONTACT, PIN, SIZE 12, FOR #12-14 AWG
2 EA
o 002324
RING TERMINAL, #16-14 AWG, BLUE, #8 STUD, VINYL
1 EA
o 026543
FUSEHOLDER: 20AMP
1 EA
o 001911
CABLE TIE, STANDARD CROSS SECTION, 7.5 BLACK
10 EA
o 008294
HEAT SHRINK, DOUBLE WALL, ADHESIVE, 1/4 4' STICK 5 IN
o 014538
HIGH TEMP SPLIT LOOM, 1/4 ID BLACK
6 FT
o 009513
15 AMP ATC FUSES/ 10 PACK
1 EA

Parts Required but not included in kit:
•

002332

BUTT CONNECTORS, NON INSULATED, #16-14 AWG

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

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Procedure:
1. Perform the Proterra approved Lockout/Tagout procedure to make the bus safe for work.
2. Using Wire Strippers, strip one end of the Green Wire (001542) to accept a Terminal.
3. Using a Crimp Tool, crimp a Pin (001268) onto the stripped end of the wire.
4. Using a Pin Extractor Tool, remove the Terminal and wire from Cavity 101 of PM900 on the
Rear Deck Harness. This is the large pass through connector.
5. Seal the removed Terminals and wire with Heat Shrink (008294).
6. Insert the Pin (001268) on the Green Wire (001542) into Cavity 101 of PM900 on the Rear
Deck Harness.
7. Route the free end of the new wire along the Rear Deck Harness to the Rear Deck VEC.
8. Using Side Cutting Pliers, cut the Green Wire (001542) to the proper length to reach the Rear
Deck VEC and add the Fuse Holder (026543).
9. Using Wire Strippers, strip the free end of the Green Wire (001542) and both wires on the
Fuse Holder (026543).
10. Using a Crimping Tool, crimp the wire onto the Fuse Holder (026543) using a Butt Splice
(002332) and Heat Shrink (008294) to cover the splice.
11. Using a Crimping Tool, crimp the Ring Terminal onto the Fuse Holder (026543).
12. Install the Fuse (009513) into the Fuse Holder (026543).
13. Using a 13mm Ratchet/Socket, install the Ring Terminal onto the 24V Switched lug on the
VEC.
14. Using a Calibrated Torque Wrench with a 10mm Socket, torque the nut securing the ring
terminal to 15 foot pounds.
15. Secure the cut wire inside the Split Loom (014538) using Electrical Tape.
16. Using a Pin Extractor Tool, remove the wire and terminal from Cavity 2 of MUX7B.
17. Reinstall this terminal into Cavity 14 of MUX7A.
18. Using Cable Ties (001911), neatly secure the wiring inside the Split Loom (014538).
19. Remove the Lockout/Tagout devices and power on the bus.
20. Ensure that the Traction Motor is enabled, and no faults are present on the vehicle.
21. Return 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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