Self-Study Program

31
Switch-over of the rear lights
Switch-over when opening the tailgate
When the tailgate is opened, the brake/tail lights and the turn signals are switched over from the rear lights in
the tailgate to the additional rear lights in the bumper. The bulbs in the rear lights in the tailgate are then
switched off. If the tailgate is closed again, the system switches back to the rear lights in the tailgate. The
additional rear lights in the bumper are again deactivated.
Switch-over in case of failure of lamps
In the case of failure of the turn signal on one side
of the vehicle or failure of both lamps for the
combined tail lights/brake lights, the system
switches over asymmetrically to the lights in the
bumper. This means that the system switches over
only to the faulty side of the vehicle. If an
asymmetric switch-over is made, this is indicated in
the dash panel insert. In the case of a switch-over
due to the failure of the main rear lights to the
additional rear lights in the bumper, the next
attempt to switch on the rear lights in the tailgate is
made in conjunction with the next terminal 15 cycle.
Rear light switch-over sequence
The convenience system central control unit J393 receives sensor information from the convenience system
central control unit 2 J773 for switching over the lights when opening the tailgate. Tailgate closed sender 1
G525 and tailgate closed sender 2 G526 are connected to the convenience system central control unit 2 J773.
If the convenience system central control unit 2 J773 receives the information "tailgate open", this information
will be relayed to the convenience system central control unit J393 via the convenience CAN bus. The
convenience system central control unit J393 thereupon switches over from the rear light in the tailgate to the
additional rear lights in the bumper. You will find information on senders G525 and G526 in the section on
convenience system central control unit 2 J773 in this self-study programme.
The convenience system central control unit is equipped with a cold and hot lamp monitoring system.
This enables it to detect the failure of the brake/tail lights and turn signals. If the failure of a lamp is detected
on one side of the vehicle, the system, switches over to the additional rear light.
Replacing the lamps
All lamps can be replaced using the vehicle's tool kit. The lamps can be accessed through 4 covers in the
tailgate.
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