Release pressure in fuel cell system with vehicle diagnosis system

AR06.00-P-1001RFW

Release pressure in fuel cell system with vehicle diagnosis system

05.12.2018

Engine

780 in model 253.992/993

1

Manual valve

2

Manual valve

 Danger

Risk of explosion caused by escaping hydrogen or overheating of the fuel tanks when working on the hydrogen system. Risk of frostbite to body parts caused by escaping gas and by touching component parts carrying gas when emptying fuel tanks. Risk of asphyxiation caused by inhalation of air diluted by hydrogen. Risk of burn injuries by coming into contact with an invisible pale blue hydrogen flame.

AS00.00-Z-0030-01B

Topical note

Notes on fuel cell system

AH00.00-P-0022-01RFW

Notes on safety-relevant components

AH00.00-Z-0019-01A

Release pressure in fuel cell system with vehicle diagnosis system.

1

Park vehicle in the open air in the hydrogen discharge area and secure it in place.

2

Perform quick test for leaks.

AR06.00-P-0003RFW

If the measured hydrogen concentration is   8000 ppm or there is an audible leak in the fuel cell system,



Prepare vehicle with major leakage in fuel system for repair

AR47.60-P-0018RFW

3

Charge the high-voltage battery to a charge level of   80 % in the open air, then remove the charging cable.

AR47.70-P-0009RFW

 The charge level of the high-voltage battery module is necessary for the diagnosis routines as well as activating different valves.

 Perform the following jobs in the open air as well.

4

Perform diagnosis-based deactivation of the start approval of the fuel cell system.



AD00.00-P-2000-04B

 To do this, select the following menu item:
Powertrain control unit (N127) 
Actuations 
Status of the start approval for the fuel cell system component.

5

Perform diagnosis-based deactivation the vehicle standby mode.



AD00.00-P-2000-04B

 To do this, select the following menu item:
Powertrain control unit (N127) 
Actuations 
Status of the start approval for the powertrain control unit component (N127).

6

Seal manual valves (1, 2) on both fuel tanks.

 The manual valves (1, 2) can be reached without lifting the vehicle and without removing the underfloor paneling.
The manual valves (1, 2) have a hexagon head with a wrench size of  7 mm.

 Torque for sealing of manual valve in valve unit

*BA47.60-P-1029-01B

7

Release pressure in fuel cell system with vehicle diagnostic device.



AD00.00-P-2000-04B

 To do this, select the following menu item:
Fuel cell control unit (N116/2) 
Actuations 
depressurization of fuel high-pressure, system pressure, operating pressure

8

Print out the pressure reduction log from the diagnostic device, sign it and place it in a clearly visible location behind the windscreen.



AD00.00-P-2000-04B

9

Perform a diagnosis-based activation of the vehicle standby mode in the powertrain control unit (N127).



AD00.00-P-2000-04B

 To do this, select the following menu item:
Powertrain control unit (N127) 
Actuations 
Status of the start approval for the powertrain control unit component (N127).

10

Drive into the workshop powered by a battery.

 Tank system

Number

Designation

Engine 780 in model 253.992/993
with code ME02 (Fuel cell)

BA47.60-P-1029-01B

Torque for sealing of manual valve in valve unit

Nm

6