Remove engine compartment lid catch
Preliminary work
- Refer to REMOVING THE FRONT HOOD SEAL .
- Refer to REMOVING THE COVER FOR THE CENTER ENGINE COMPARTMENT .
Only on vehicles with active pedestrian protection
Danger! Immobilization period-threatening injuries!
- All work on pyrotechnic parts may be carried out by technically experienced and appropriately trained personnel only.
- Replace any damaged part or ones that have been dropped.
- For additional information see: SAFETY REGULATIONS FOR HANDLING COMPONENTS WITH GAS GENERATORS .
Deactivating the 48 V electrical system
Precondition
Ignition is switched off.
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.
Risk of short circuits! Risk of fire!
- Make sure that there is no charger connected to the jump start terminal in the engine compartment.
Damage to the 48-V battery
If a 48-V battery that is disconnected from the electrical system is activated, the battery electronics will be damaged.
- Only ever activate the 48 V electrical system when the 48 V battery is fully connected up.
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.
Check
NOTE: TECHNICAL INFORMATION
Zero voltage (48 V electrical system switched-off) 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.
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).
- 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.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.
Deactivate electrical system
NOTE: TECHNICAL INFORMATION
Follow the vehicle-specific instructions described in the additional information. - Deactivate the vehicle electrical system as described in the additional information.
- Unlock plug connection (1) and disconnect.
- Loosen screws (2).
- Feed out the hood lock in an upwards direction.
- Detach the cable (3) and remove the hood lock.