Mercedes-Benz GL-Class 2014 Owners Manual - Manual (Page 272)

Trailer power supply
! You can connect accessories with a
maximum power consumption of 240 W to
the permanent power supply.
You must not charge a trailer battery using
the power supply.
The trailer socket of your vehicle is equipped
at the factory with a permanent power supply.
The permanent power supply is supplied via
trailer socket pin 4.
The trailer's permanent power supply is
switched off in the event of low vehicle supply
voltage and after six hours at the latest.
A qualified specialist workshop can provide
more information about installing the trailer
electrics.
270
Towing a trailer
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