23-FL-005H Service Bulletin/Repair Instructions

GROUP
NUMBER
FUEL SYSTEM

DATE
Technical Service Bulletin
23-FL-005H

MODEL(S)
AUGUST 2023
NEXO FUEL CELL

(FE)
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
This TSB supersedes 22-FL-005H to revise the vent manifold assembly and venting hose.

Description: This bulletin provides information on how to properly vent Hydrogen from a Nexo FCEV

for maintenance or repairs.

Applicable Vehicles (Certain): All Nexo (FE) Fuel Cell Electric Vehicles (FCEV)

! CAUTION

The TSB repair procedure MUST be performed at an authorized Hyundai NEXO fuel cell vehicle

dealer and by a Hyundai Service Technician who has successfully completed the Fuel Cell Electric

Vehicle Training Instructor Led Training course (SVCHFCEVTRAIN222_1097).

For Personal Protective Equipment (PPE) inspection and testing requirements, refer to OSHA

standard 1910.137 - Electrical Protective Equipment; and the NEXO shop manual for PPE usage.

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”)

Special Service Tool (SST) Information:

Tool Name
HPR to Vent Hose Adapter (1)
Figure
1
2
Vent Manifold Assembly (2)

Ground Wire (3)
Remarks

Qty: 1

Qty: 1
3
4
Qty: 2
35’ Venting Hose (4)
Qty: 1
Portable Vent Hydrogen Stack

Assembly
Follow TSB 20-FL-009H

P/N: HVS01
Quick Connector Remover

(1/2”)
Follow TSB 20-FL-009H

P/N: 09356-4W110
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)
Required Tools:

• Global Diagnostic Scan Tablet (GDS-M)

• Hydrogen Gas Detector

• Personal Protective Equipment (PPE)

• Torque Wrench

• Floor Jack, Wheel Chock, Jack Stands

• Various size metric sockets, 6mm hex socket

• Tape Measure

Reference Material:

Media Location
Hyundaitechinfo.com
i
•

•

•

•

•

•
Title

Nexo Service

Manual
Vehicle Communication Interface II (VCI-II)

Digital Volt Ohm Meter (DVOM)

Watch/clock

19mm and 24 mm Combo Wrenches

Ratchet and extensions as needed

Tapered Stopper
Name/Description

Hydrogen Storage System
TSB 20-FL-009H
Portable Vent Stack Assembly Procedure
TSB 15-GI-001
ECU Update Procedure for Tablet-Based GDS Mobile
Information
Considerations Before Venting:

•

•

•
•
Ensure the venting procedure performed at an approved Hydrogen venting location.

Ensure the vent stack grounding wire is attached to an approved ground connection.

Verify that the required tools, equipment, and personal protective equipment (PPE) are

ready, available, and in proper working condition.

Predetermine the desired final tank pressure based on the repair type.
TSB #: 23-FL-005H
Page 2 of 23

SUBJECT:
SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
Service Procedure:

A. Determine the Hydrogen Tank Pressure Using GDS-M

B. Assemble the Portable Hydrogen Vent Stack (HVS01) Kit

C. Vehicle Preparation and Staging

D. 12 Volt and High Circuit Disconnection

E. Hydrogen Tank Shut-off Valve

F. Releasing Residual Fuel Supply Pressure (GDS-M Procedure)

G. Releasing Residual Fuel Supply Pressure (Manual Procedure)

H. Installing the Vent Manifold Assembly

I. Venting the Hydrogen Storage Tanks
!
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.
TSB #: 23-FL-005H
Page 3 of 23

SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
Type of Repair

Routine Maintenance

Maintenance / Repair of the Hydrogen System

Components

Maintenance / Repair of the Hydrogen Storage

Tanks / Fill Lines. Open-Flame Activities or

Welding within 18 inches (455 mm) of the

hydrogen storage containers and lines
Venting Required Yes / No

No, does NOT require venting

Yes, if Hydrogen storage tank pressure is above

1,100 PSI

Yes, Hydrogen tanks must be completely vented
Refer to the beginning of the procedure on page 5 for detailed instructions.

Vent Manifold Assembly

Review the function of each component before performing this service procedure. The reference

picture below identifies the basic components of the manifold assembly.
Stainless Steel (SUS) Tube
Quick Connector
Ball Valve
Magnetic Clamp
Pressure Gauge
Stainless Steel (SUS) Tube – Connects to the high-pressure regulator (HPR) during the venting

procedure.

Quick Connector – Couples the venting hose to the vent stack assembly.

Ball Valve – Controls the Hydrogen flow when venting the Hydrogen storage tanks.

Pressure Gauge – Monitors the HPR outlet pressure during the venting procedure.

Magnetic Clamp – Secures the vent manifold assembly to the body during the venting procedure.
TSB #: 23-FL-005H
Page 4 of 23

SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
A. Determine the Hydrogen Storage Tank Pressure Using GDS-M

1.
Connect the GDS-M, select the HMU (A), and

then check the storage tank pressure (B).

Refer to the table on page 4 for the Type of

Repair to determine what pressure is allowed

in the storage tanks prior to beginning

maintenance or repairs.
A
If the tank pressure is less than 1,100 PSI,

proceed to Section D.

If the tank pressure is greater than 1,100

PSI then proceed to Section B.
i
Information
Before performing the service procedure,

verify that the GDS-M is adequately

charged.
B
TSB #: 23-FL-005H
Page 5 of 23

SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
B. Assemble the Portable Hydrogen Vent Stack (HVS01) Kit

1.
Refer to TSB 20-FL-009H to assemble the

HVS01 portable hydrogen vent stack.
2.
Gather the following SST’s for venting the

FCEV.

•

•

•

•
i
HPR to Vent Hose Adapter (A) – Qty: 1

Vent Manifold Assembly (B) – Qty: 1

Ground Wire (C) – Qty: 2

35’ Venting Hose (D) – Qty:1
A

B
C
Information
D
Do NOT connect the components for the

Portable Hydrogen Vent Stack or FCEV

Venting SST to other venting systems.
When using the portable vent stack, follow the minimum spacing distances.

Minimum Spacing From Hydrogen Vent Exit.
Feet
Above adjacent equipment
2
Above rooftops
5
Spherically, to Class 1, Division 1 Electrical Classification
5
Grade level to Hydrogen vent exit
10
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
15
Lot lines; air intakes; building/Structure opening; open flames or welding
40
TSB #: 23-FL-005H
17

20
Page 6 of 23

SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
C. Vehicle Preparation and Staging
i
Information
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 from the

assembled and properly grounded portable

Hydrogen vent stack (A). The vehicle must be

outside the coned off safety circle (B).

!
A
WARNING
Do NOT vent Hydrogen during electrically

conductive weather conditions.

While the venting hose is connected to the

vent manifold assembly, no personnel

should be allowed into the safety circle.

Ensure the portable vent stack is properly

grounded.

2.
If the vehicle has been in storage for several

days, run the fuel cell for a sufficient amount of

time to fully charge the 12-volt battery.
3.
Do NOT leave the headlight switch in auto

mode.
B
Turn off all lights and accessories including:

• Heater / air conditioner

• Fan

• Audio

• Heated seats

• Rear defroster

4.
Place the vehicle in park, apply the parking

brake, roll down the windows as necessary,

and open the rear hatch.
5.
Scan and record all DTCs before performing

service procedure.

Ensure the Start Stop Button (SSB) is OFF,

and the fuel stack is NOT in Ready Mode. Wait

at least 3 minutes. Use appropriate PPE when

proceeding with Section D.
6.
TSB #: 23-FL-005H
Page 7 of 23

SUBJECT:
SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
D. 12 Volt and High Voltage Circuit Disconnection

1.
In the rear cargo area, remove the floorboard

(A) and cargo tray (B) to access the 12-volt

battery connector and high voltage battery

safety plug.

A
B
2.
Disconnect the 12-volt battery negative (–)

connector.

Refer to the shop manual:

• Battery Control System > High

Voltage Battery Handling Guide >

High Voltage Shut-off Procedure.
TSB #: 23-FL-005H
Page 8 of 23

SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
3.
Remove the metal shield (C) to access the

orange-colored high voltage safety plug (D).
!
WARNING
C
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.
D
TSB #: 23-FL-005H
Page 9 of 23

SUBJECT:
SUBJECT:
4.
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
Follow images 1 - 4 to remove the orange high

voltage safety plug.
Safety Plug Removal
Store the removed safety plug (E) in a secure

location outside and away from the vehicle.

1
3
Press down on the safety

plug lever.
2
Pull the green safety plug

lock tab.
4
Remove the safety plug.
Safety Plug Removal
E
5.
Wait 5+ minutes to allow the high voltage

system capacitor to discharge.
TSB #: 23-FL-005H
Page 10 of 23

SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)
SUBJECT:
6.
Open the hood and remove the junction box

trim (F) and cover (G).

Tightening Torque:

lb-ft
8
lb-in
96
N.m
11

F
G
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.
i
Measure

Voltage Here
Information
If the measured voltage is below 30V, the

High Voltage Circuit is properly shut down.
!
–
+
DANGER
The High Voltage Junction Box (HVJB) may

be electrically energized up to 450 volts.
TSB #: 23-FL-005H
Page 11 of 23

SUBJECT:
SUBJECT:
VENTING NEXO FUEL CELL ELECTRIC VEHICLES (FCEV)

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