GROUP
FUEL SYSTEM

Technical Service Bulletin
SUBJECT:

DATE
December, 2020

NUMBER
20-FL-008H-1
MODEL(S)
NEXO FUEL CELL
(FE FCEV)

VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

This bulletin supersedes TSB# 20-FL-008H by revising the requirements for venting the
Hydrogen tank prior to conducting repairs.
Description:
This bulletin provides information on how to properly vent Hydrogen from a Nexo FCEV for
maintenance or repairs.
Applicable Vehicle: 2019-2020MY Nexo Fuel Cell
Warranty Information:
Normal Warranty Applies
Required Tools & Equipment
 Portable Hydrogen Vent Stack (HVS01) Kit with Venting Manifold and Venting Hoses
 Global Diagnostic Scan Tablet (GDS-M)
 Vehicle Communication Interface II (VCI-II)
 Hydrogen Gas Detector
 Digital Volt Ohm Meter (DVOM)
 Personal Protective Equipment
 Watch/clock
 Torque Wrench
 19mm and 24 mm Combo Wrenches
 Floor Jack, Wheel Chock, Jack Stands
 Quick Connector Remover Tool
 Various size metric sockets, 6mm hex socket  Ratchet and extensions as needed
 Tape Measure
 Tapered Stopper
Reference Materials
Media Location
Hyundaitechinfo.com

Title
Nexo Service Manual

Hyundaitechinfo.com

TSB 20-FL-009H

Hyundaitechinfo.com

TSB 15-GI-001

Name / Description
Hydrogen Storage System
Portable Vent Stack
Assembly Procedure
ECU Update Procedure
For Tablet-Based GDS Mobile

Before Venting Questions/Considerations:
 Is the venting procedure being completed at a pre-defined Hydrogen venting location?
 Is a suitable grounding connection available, and in proper working condition?
 Are the required tools, equipment and PPE ready, available and in proper working condition?
 Has the desired venting endpoint of the tanks been determined based on type of repair?

Circulate To: General Manager, Service Manager, Parts Manager, Warranty Manager, Service
Advisors, Technicians, Body Shop Manager, Fleet Repair

SUBJECT
:

VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Review the following venting requirements prior to conducting repairs on a Nexo FCEV.
Communicate with all applicable authority groups for additional venting requirements at your location.
Circumstances when venting Hydrogen from FCEV is necessary.
1. For routine maintenance work.
o Hydrogen storage tanks venting is not necessary so long as maintenance or repairs do not
involve; parts or components that may contain hydrogen (storage tanks, fill lines, delivery
lines, fuel cell) and/or the high voltage system components.
2. For maintenance/repair of Hydrogen system components (excluding Hydrogen storage
tanks and fill lines) and/or High Voltage system components.
o Hydrogen storage tanks pressure must be below 500psi.
3. For maintenance/repair of the Hydrogen storage tanks/fill lines; where open flame
activities or welding occurs within 18 inches (455 mm) of the Hydrogen storage tanks
and lines.
o Hydrogen tanks must be completely vented.
Follow the Hydrogen Storage Tanks Venting Procedure. (Page 4)

!

WARNING

Precautions when a Hydrogen leak is suspected
1. Move the vehicle outdoors.
2. Turn off all electrical equipment, eliminate possible ignition sources, open all windows/doors.
3. Use a hydrogen leak detector to find the cause of the leak.
4. Vent Hydrogen from the vehicle as needed for repairs.
5. Replace the component(s) as necessary to repair the leak.
6. After above procedures are completed, use suitable Hydrogen leak detector and recheck for
any Hydrogen leak.
This Fuel Cell Electric Vehicle (FCEV) utilizes up to 450 volts and compressed Hydrogen gas
stored up to 10,000 psi. Only qualified, trained technicians should perform the venting procedure.
Before performing the service procedure, ensure the proper Personal Protective Equipment
(PPE) is worn to prevent injury. Verify PPE is not expired and in proper working condition.

!

CAUTION

When replacing any of the hydrogen storage system components, there may be leakage in the
connecting part. Inspect for Hydrogen leaks after repairing / replacing any component that is part of
the Hydrogen system. (Refer to Hydrogen Storage System – “General Information”)

TSB #: 20-FL-008H-1

Page 2 of 15
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VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Manifold Assembly:
Review the function of each Manifold Assembly component before performing this service procedure.
The reference picture below outlines the basic function(s) of the manifold assembly.

TSB #: 20-FL-008H-1

Page 3 of 15
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VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Hydrogen Storage Tanks Venting Procedure:
A. Portable Hydrogen Vent Stack (HVS01) Kit
1.

Assemble the portable Hydrogen Vent Stack Part Number (HVS01) using TSB 20-FL-009H.

Locate the FCV Venting Manifold Kit which includes the following:
Kit Contents –
 Manifold Assembly
 Auxillary gas hose
 Three 10 foot long venting
hoses

Do not connect any part of the Portable Hydrogen Vent Stack, Venting Manifold, or Venting
hose to any other venting system used for any other purpose
When using the Portable Vent Stack, follow the minimum spacing distances.
Feet
2
5
5
10
15
17
20
40

Minimum Spacing From Hydrogen Vent Exit.
Above adjacent equipment
Above rooftops
Spherically, to Class 1, Division 1 Electrical Classification
Grade level to hydrogen vent exit
Spherically, to Class 1, Division 2 Electrical Classification
Overhead utilities; Non-fire-rated buildings; Flammable, combustible or
other hazardous materials process or storage systems
Exposed persons and parked cars
Lot lines; Air intakes; Building/Structure opening; Open flames or welding.

Ensure the Portable Vent Stack is properly grounded.

TSB #: 20-FL-008H-1

Page 4 of 15
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VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

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B. Vehicle Preparation and Staging:
!

WARNING

Do not vent Hydrogen during electrically conductive weather conditions.

NOTICE
Before performing the service procedure, verify that the GDS-M is adequately charged.
1.

In an outdoor area approved for Hydrogen venting, the vehicle must be 15 feet or greater from
the assembled and properly grounded Portable Hydrogen Vent Stack. The vehicle must be
outside the coned off safety circle.
While the vent hose is connected to the manifold assembly, no personnel should be allowed
into the safety circle.

2.

If the vehicle has been in storage for several days, run the fuel cell for a sufficient amount of
time to ensure that the 12 volt battery is fully charged.

3.

Ensure that the 12 volt battery will not become discharged during the venting procedure by
turning off all lights and accessories including heater/air conditioner, fan, audio, heated seats,
rear defroster, etc.

4.

Do not leave the headlight switch in auto mode.

5.

Place the vehicle in park.

6.
7.

Apply the parking brake, roll down the windows as necessary, and open the rear hatch.
Scan and record all DTCs before performing service procedure.

8.

Ensure the Push Button Start Stop (PBSS) is off, and the fuel stack is not in Ready Mode.
Wait at least 3 minutes, and use appropiate PPE before proceeding to Section C.

TSB #: 20-FL-008H-1

Page 5 of 15
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VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

C. 12 Volt and High Voltage Circuit Disconnection
1.

In the rear cargo area, remove the floorboard and cargo tray to access the 12 volt battery
connector and high voltage battery Safety Plug.

2.

Disconnect the 12 volt battery negative (-) connector.

!

WARNING

Before performing the service procedure, ensure proper Personal Protection Equipment (PPE)
is worn to prevent injury. Verify PPE is not expired and in proper working condition.

TSB #: 20-FL-008H-1

Page 6 of 15
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VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

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3.

Remove the metal shield to access the High Voltage Safety Plug.

4.

Follow 1- 4 below to remove the orange high voltage safety plug.
Store the removed safety plug in a secure location outside and away from the vehicle.
Safety Plug Removal
Safety Plug Removal

1

3
5.

Press down on the safety
plug lever

2

Pull the green safety plug
lock tab

4

Remove the safety plug

Wait 5+ minutes to allow the high voltage system capacitor to discharge.

NOTICE
The High Voltage Junction Box (HVJB) cover is located under the hood and on top of
the fuel stack in the fuel cell compartment.

!

DANGER

The High Voltage Junction Box (HVJB) may be electrically energized up to 450 volts.

TSB #: 20-FL-008H-1

Page 7 of 15
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6.

VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

Remove the junction box trim and cover.

HVJB Cover

Junction Box Trim

High voltage junction box cover: Assembly bolt torque. 9.8 - 11.8 N.m (1.0 - 1.2 kgf.m, 7.2 - 8.7 lb-ft

7.

Using a Digital Volt Ohm Meter (DVOM), measure the voltage across the inverter positive and
negative bus bar terminals to inspect for capacitor discharge. If the measured voltage is
below 30V, the High Voltage Circuit is properly shut down.

-_
Measure Voltage
Here