Deactivating the 48 V electrical system

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Precondition

Ignition is switched off.

WARNING: Deactivate the 12-V electrical system.
Risk of short circuits! Risk of fire!

Make sure that there is no battery charger connected to the jump start terminal in the engine compartment.
For vehicles with additional electrical systems (48 V electrical system, high-voltage vehicle electrical system), this absolutely must be deactivated before the vehicle battery is disconnected.

WARNING: Deactivate the 48-V electrical system.
Risk of short circuits! Risk of fire!

Make sure that there is no charger connected to the jump start terminal in the engine compartment.

NOTE: RISK OF DAMAGE
Damage to the 48-V battery
If a 48-V battery disconnected from the on-board electrical system is activated, the battery electronics are damaged.

Only ever activate the 48 V electrical system when the 48 V battery is fully connected up.

NOTE: TECHNICAL INFORMATION
Observe notes on the 48-V battery. See additional information NOTES ON THE 48-V BATTERY .

Deactivate the 48 V electrical system by opening the hood.
Deactivation is automatic.

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Check

NOTE: TECHNICAL INFORMATION
A display of the absence of voltage (48 V electrical system switched off) in the additional electrical storage is only displayed in PAD mode.
Press the START-STOPPING button quickly 3 times without stepping on the brake pedal to establish the PAD mode.
Check the de-energized state in the instrument cluster (KOMBI) in the PAD mode.

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Desired state
The Check Control message "48 V electrical system." switched off (1) is displayed.
Result

» Absence of voltage cannot be specified with the Check Control message "48 V electrical system switched off." (1). Work start is not permitted.

Measure
- Repeat the "deactivate 48 V electrical system" service function.
- Vehicle management > service function > voltage supply > deactivate 48 V electrical system
Only if the Check Control message "48 V electrical system switched off." (1) is displayed in the instrument cluster (KOMBI), the 12V battery may be disconnected.

Result

» Zero potential cannot be determined with the Check Control message "48 V electrical system switched off." or "Electrical additional storage switched off." (1). Start of work is not permitted.

Measure

Disconnect 48V additional storage with fault memory entry Relay jammed closed Result

» The Check Control message reports that 48 V electrical system is switched off.

Measure
- Exit PAD mode by pressing the START-STOPPING button once without stepping on the brake pedal.
  "Disconnect the negative battery cable of the 48-V battery" work can be started.
Unlock and disconnect the CAN bus plug connection (1) of the gear sensor.
Release the clip (2).

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Loosen nut (1).
Detach the negative battery cable (2) of the 48-V battery from the negative battery terminal, set to one side and secure.

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WARNING:
Unprotected battery terminals.
Risk of short circuits! Risk of fire!
- Cover the vehicle battery.
Cover the vehicle battery with the special tool 2 452 007 as shown.
Position the battery ground lead (1) as shown.

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