Self-Study Program

24
Control units
Battery replacement
When the vehicle battery is replaced, the energy management control unit J644 must be encoded.
This is necessary to adapt the new battery (size, manufacturer, new condition) to the energy management
system. Only then will the energy management system function with maximum efficiency and precision.
The energy management control unit J644 may only be encoded after a battery is replaced. Otherwise, faults
will be produced in the vehicle due to incorrect assessment of the battery state and loss of important history
data, which is required, among other things for testing the battery with the VAS tester.
Trickle charge
To conserve battery power in showroom vehicles
and vehicles in the workshop, a VAS 5095A,
VAS 5900 or VAS 5903 charger must be connected to
the designated slave start connector in the engine
compartment on the left-hand side. This will prevent
exhaustive discharging of the battery.
364_016
Slave start connector
Positive
Slave start connector
Negative
Disconnecting the vehicle battery
To disconnect the earth wire of the vehicle battery, it is not necessary to fold up the seat.
The battery's earth wire of the battery can, when necessary, be disconnected at the earth connector in front of
the left-hand seat.
364_017
364_018
Cover in front of left-hand seat Earth connector