Mercedes-Benz Body & Equipment Guideline for Metris - BM 447, Version November 27, 2015.
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9.5 Lighting
9 Electrical system
9.5.3 Exterior lamps
Lamp monitoring
The signal acquisition and actuation module (SAM)
monitors all outputs for open load (wire break) and
short circuit. If a lamp is not connected or is over-
loaded, a fault entry is stored in the memory of the
SAM control unit. The vehicle owner or the driver
must be informed. It is recommended that an entry
be made in the service booklet. The fault entry must
be addressed during a service if read out using
XENTRY Kit.
Additional lamps
Additional lamps must be connected via the PSM
or a separate cube relay. A standard cube relay
(R
i
> 80 ohm) can optionally be connected in parallel
with the exterior lamps (with the exception of the cen-
ter high-mounted brake lamp, turn signals, licence plate
illumination, side markers and clearance lamps). This
will not have any negative effect on lamp monitoring.
EK1/ED5/U
R >80
BAT
N82.10-2485-00
B
A
i
Connection of an additional lamp
A Scope of the basic vehicle
B Scope of the upfitter
9.5.4 Interior lamps
All interior lamps can be replaced by other body-manu-
facturer-specific lamps. The interior lamps are operated
via read-back switches networked through the SAM
(signal acquisition and actuation module).
The system is only monitored for short circuits, max-
imum load 80 W. The lights are dimmed as standard.
Dimming must be deactivated in the SAM if fluorescent
lighting or relief relays are used.
The read-back switch must always be connected to the
SAM, otherwise the interior lamps cannot function.
U
AUTO
ON
SAM
N82.20-2182-00
A
BAT
Read-back switch switching principle
U
BAT
Interior lighting power supply (+ 12 V)
AUTO Lighting controlled by SAM, e.g. when door
opened
ON
Interior lamp permanently lit
A
Read-back switch (interior lighting)
