Measures to be taken before working on high-voltage on-board electrical system
The vehicle's high-voltage on-board electrical system must not be charged during all service, maintenance, diagnosis and repair operations. The charging cable must be unplugged at the vehicle end.
Exception: Charging is permitted, if it is required for diagnosis during the test procedure.
A risk of injury exists for pre-programmed or remote-controlled pre-entry climate control (PreCon) through the automatic starting up of fans, blowers, pumps in the water circuit or activation of the high-voltage PTC heater and the refrigerant compressor. To suppress the remote PreCon functions (if present) and on-board electrical system support during repair work, they must be switched off (if present) in the instrument cluster or the engine hood/maintenance flap or the tailgate or rear-end door must be opened.
The high-voltage on-board electrical system must be in a voltage-free status before any work is performed on it. The de-energized condition of the high-voltage on-board electrical system must be assured for the duration of the work to be performed.
The 3 safety rules must be observed and adhered to when conducting such work:
Disable (de-energize)
Secure against reactivation.
Check and secure safe isolation from supply.
The disabling and commissioning procedure must be documented and affixed to the vehicle in a visible location.
Measures to be taken when working on high-voltage on-board electrical system
Check the high-voltage on-board electrical system for external damage such as, e.g. damage caused by animals, chafe marks, accident damage and defects. Defective high-voltage components or lines must always be replaced. Any repair/modification of the high-voltage components or the lines of the high-voltage on-board electrical system is not permissible.
Marking
All components of the high-voltage on-board electrical system are marked with a yellow adhesive warning label on which the pictogram for high-voltage is represented.
All high-voltage conducting electrical lines are identified by a warning color (orange).
Qualification measures
All activities on vehicles with high-voltage on-board electrical system and the assessment of the transport safety of lithium-ion batteries (high-voltage batteries) must only be performed by appropriately qualified employees.
Work-related safety instructions by company
To perform "simple" activities, the employees must be made aware of any special points, hazards, protective measures and rules of conduct with regard to the high-voltage on-board electrical system when they are instructed in work-related safety aspects in the company.
The following "simple" activities may be conducted after a successfully completed course of safety instruction:
Operation (driving, fueling/charging, cleaning)
Tires (checking condition, changing)
Checking/refilling coolant, washer fluid, oil.
Changing wiper blades/adjusting spray nozzles
Charging 12 V battery; checking/changing 12 V fuses.
Reading out diagnosis (actual value, quick test).
Retrofitting accessories (without WIS description).
Reception incl. checking for service measures not yet performed
Explanation of vehicle-specific functions (during sale/at vehicle delivery)
High-voltage awareness course (requirement for high-voltage basic training)
All repairs, maintenance and diagnosis work of high-voltage components on de-energized vehicles with a high-voltage on-board electrical system
Removal and installation of high-voltage components on de-energized vehicles with a high-voltage on-board electrical system
High-voltage basic training T0001F (requirement for high-voltage product qualification)
Theoretical basics on high-voltage components
High-voltage safety measures
High-voltage on-board electrical system
First aid
Working safely on high-voltage vehicles
High-voltage product qualification (requirement for manual disabling and high-voltage special checks)
Conduct and document the diagnosis-based disabling of high-voltage on-board electrical system
Design and function of high-voltage components
Control and display concept
Transport capability assessment of lithium-ion batteries (high-voltage batteries)
High-voltage special checks, manual disabling, insulation monitoring (requirement for fault diagnosis of high-voltage on-board electrical system)
Manual disabling with personal protective equipment (PSA)
Conduct and document insulation check on high-voltage on-board electrical system.
Conduct and document voltage proof test.
Perform and document protective ground conductor test and insulation resistance test.
Fault diagnosis for high-voltage on-board electrical system
Fault diagnosis of on high-voltage on-board electrical system
Diagnosis of high-voltage batteries
Function of on-board electrical system support
The following overview presents the operations and training requirements:
Country-specific modifications, deviations, additional requirements or legal requirements must be observed.
| Qualification |
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High-voltage requirement not necessary | High-voltage requirement not necessary | Requirement: High-voltage awareness course | Requirement: High-voltage basic training | Requirement: High-voltage product training | Requirement: High-voltage training, manual disabling | |
"Simple" activity outside the high-voltage on-board electrical system: | Yes | Yes | Yes | Yes | Yes | Yes |
General repairs on vehicles with high-voltage on-board electrical system: | No | Yes | Yes | Yes | Yes | Yes |
Diagnosis-based disabling of vehicle: * | No | No | No | Yes | Yes * | Yes |
Manual disabling of vehicle with personal protective equipment: | No | No | No | No | Yes ** | Yes ** |
* Diagnosis-based high-voltage disabling is allowed if the product training for that particular vehicle has been completed successfully. Diagnosis-based disabling must always be attempted before manual disabling.
** Manual disabling permitted in accordance with WIS specification for all models (except vehicles in the Metropolitan concept, if available).
Measures to be taken before working on gas drive systems
If there are any indications of leaks and problems with the gas drive system, the vehicle may only be parked outdoors for a long period of time when secured. Furthermore, it must be marked with a clearly visible sign or similar such as to prevent any inadvertent running-in of the vehicle. A sufficient following distance must be maintained to adjacent buildings and vehicles in the immediate vicinity (radius 10 m).
Before starting work, make sure that all ignition sources are removed and personal protective equipment (PPE) is worn. Make sure that there is sufficient ventilation in the surrounding area with by changing the air at least three times per hour at a distance of three meters from the vehicle's shutoff valve. The gas shutoff valves on the gas cylinders must be closed before starting any repair work and the gas lines must be emptied.
Measures for draining the fuel tank (hydrogen H2)
The hydrogen vehicle may only be drained in a specially marked area and outdoors. This activity is strictly prohibited during thunderstorms. The draining area must be cordoned off in a radius of at least 5 m around the draining vent. A clearly recognizable warning of an explosive atmosphere must be displayed at the entrances. The distance to buildings, windows etc. must be far enough removed to ensure that the rising hydrogen cannot collect under roofs, curtains, and any ventilation blind spots, etc. There must be no vehicles within the draining area and no other work performed during the draining process. The vehicle and the draining vent must be appropriately grounded. The employee must discharge himself/herself electrostatically at a suitable point before starting to drain the hydrogen vehicle. During the draining procedure or, where applicable, in the event of any uncontrolled gas leakage, electric workshop equipment may not be used (cordless screwdrivers, electric wheel lifts, etc.). The specified drain vent version is given in the Mercedes-Benz specific repair, maintenance and diagnostic documentation.
Measures for discharging the fuel tank (natural gas)
Where possible, you should avoid discharging the gas of the gas system into the atmosphere because natural gas is a greenhouse gas. If discharging cannot be avoided, the specifications from the vehicle or system manufacturer must always be observed. Gas systems may only be discharged outdoors. A designated area of approx. 10x10 m is required for this activity. No other vehicles may be located in this area during the process and no other work may be performed. The discharge area should preferably be equipped with a lightning protection system (lightning rod). This activity is strictly prohibited during thunderstorms. The discharge area should have a means to ground the vehicle (e.g. by using a steel rod hammered into the ground). If the discharge area is partially or completely roofed over, you must ensure that the escaping gas can flow freely upwards.
Marking
Information labels for hydrogen (H2) are attached in the engine compartment, fuel filler flap and on the fuel tanks. All components of the high-voltage on-board electrical system are marked with a yellow adhesive warning label on which the pictogram for high-voltage is represented.
All vehicles with natural gas engine must be identified as such by means of a warning about the natural gas system at easily visible locations.
User-related safety instructions from the company
To perform "simple" activities, the employees must be made aware of any special points, hazards, protective measures and rules of conduct with regard to the gaseous-fuel drive system when they are instructed in work-related safety aspects in the company.
Qualification measures
All activities on vehicles with gaseous-fuel drive systems and the assessment of the transport safety of lithium-ion batteries must only be performed by appropriately qualified employees. The country-specific requirements and laws must always be observed.
Qualification 1 | Qualification 2 | |
Activity (hydrogen system) | High-voltage awareness raising | Product qualification for F-CELL support points (5 days) |
"Simple" activity outside the high-voltage and gaseous-fuel drive system: | Yes | Yes |
Activities within the high-voltage and gaseous-fuel drive system: | No | Yes |