2020 MERCEDES-BENZ METRIS trailer

and the noseweight of the trailer drawbar
(TWR).
Trailer power supply
! Incorrect wiring of the connector plug
could, under certain circumstances, cause
malfunctions in the vehicle's other elec-
tronic systems. We therefore recommend
having the connector plug wired at a quali-
fied specialist workshop.
! You can connect accessories with a maxi-
mum power consumption of 240 W
to the
permanent power supply.
You must not charge a trailer battery using
the power supply.
Your vehicle may be equipped with various
electrical installations for trailer towing.
Depending on your trailer, you may need an
adapter to connect the electrical system of the
trailer with that of the vehicle.
The trailer socket of your vehicle is equipped
at the factory with a permanent power supply.
The permanent power supply is on the trailer
socket pin assignment 4.
Note that the permanent power supply of the
trailer is not switched off when the on-board
voltage is low. This can completely discharge
the starter battery of your vehicle.
Further information on the electrical equip-
ment currently installed on your vehicle and on
installing trailer electrics can be obtained at
any qualified specialist workshop. Towing a trailer
173
Driving and parking Z

Lights
Display messages
Possible causes/consequences and
M Solutionsb
Check Left Low Beam
or
Check Right Low
Beam The left or right-hand low-beam headlamp is faulty.
X
Change the bulb ( Y page 105).b
Chk. Trailer L.
Turn Sig.

or Chk.
Trailer R. Turn
Sig. The left or right-hand trailer turn signal lamp is faulty.
X
Change the bulb (see the trailer manufacturer's operating instruc-
tions). b
Chk. Trailer Brake
Lamp The trailer brake lamp is faulty.
X Change the bulb (see the trailer manufacturer's operating instruc-
tions). b
Chk. Trailer L.
Tail Lamp

or Chk.
Trailer R. Tail
Lamp The left or right-hand trailer tail lamp is faulty.
X Change the bulb (see the trailer manufacturer's operating instruc-
tions). b
Auto Lamps Inopera‐
tive The light sensor is faulty. The automatic headlamp feature is mal-
functioning.
X
Switch the light functions on/off manually (Y page
99).
X Visit a qualified specialist workshop. b
Chk. Rear L. Turn
Signal

or Chk.
Rear R. Turn Signal The rear left-hand or rear right-hand turn signal is faulty.
X Change the bulb (Y page 105).b
Chk. Front L. Turn
Signal

or Chk.
Front R. Turn Sig‐
nal The front left-hand or front right-hand turn signal is faulty.
X Change the bulb (Y page 105).b
Chk. Center Brake
Lamp The high-mounted brake lamp is faulty.
X
Visit a qualified specialist workshop. b
Chk. L. Tail/
Brake Lamp

or Chk.
R. Tail/ Brake Lamp The left or right-hand tail lamp/brake lamp is faulty.
X Change the bulb (Y page 105).202
Display messages (vehicles without steering wheel buttons)
On-board computer and displays

Display messages
Possible causes/consequences and
M Solutionsb
Check Left High
Beam
or Check
Right High Beam The left or right-hand high-beam headlamp is faulty.
X
Change the bulb ( Y page 105).b
License Plate Lamp The left or right-hand license plate lamp is faulty.
X Visit a qualified specialist workshop. b
Switch Off Lights The lights are still switched on when you leave the vehicle. An addi-
tional warning tone sounds.
X Turn the light switch to à or $.b
Check Left Fog Lamp
or
Check Right Fog
Lamp The left-hand or right-hand front fog lamp is faulty.
X Visit a qualified specialist workshop. b
Rear Fog Lamp The rear fog lamp is faulty.
X Change the bulb (Y page
105).b
Chk. Front L. Park‐
ing Lamp

or Chk.
Front R. Parking
Lamp The front left or front right parking lamp or standing lamp is faulty.
X Change the bulb ( Y page 105).b
Backup Light The left or right-hand backup lamp is faulty.
X Change the bulb (Y page
105).b
Check Left Tail
Lamp

or Check
Right Tail Lamp The left or right-hand tail lamp is faulty.
X Change the bulb (Y page 105).b
Malfunction The exterior lighting is faulty.
X Visit a qualified specialist workshop. Vehicles with trailer tow hitch: a fuse may be defective.
X Check the fuses and if necessary replace any blown fuses (see
the "Fuse allocation" supplement).
X If the display message does not disappear, consult a qualified
specialist workshop. b
Chk. L. Day Run‐
ning Lgt.

or Chk.
R. Day Running Lgt. The left or right-hand daytime running lamp is faulty.
X Change the bulb (Y page 105).Display messages (vehicles without steering wheel buttons)
203
On-board computer and displays Z

Lights
Display messages
Possible causes/consequences and
M Solutionsb
Check Left Low Beam
or
Check Right Low
Beam The left or right-hand low-beam headlamp is faulty.
X
Change the bulb ( Y page 105).b
Check Trailer Left
Turn Signal

or
Check Trailer
Right Turn Signal The left or right-hand trailer turn signal lamp is faulty.
X
Change the bulb (see the trailer manufacturer's operating instruc-
tions). b
Check Trailer
Brake Lamp The trailer brake lamp is faulty.
X Change the bulb (see the trailer manufacturer's operating instruc-
tions). b
Check Trailer Left
Tail Lamp

or Check
Trailer Right Tail
Lamp The left or right-hand trailer tail lamp is faulty.
X Change the bulb (see the trailer manufacturer's operating instruc-
tions). b
Auto Lamp Function
Inoperative The light sensor is faulty. The automatic headlamp feature is mal-
functioning.
X
Switch the light functions on/off manually (Y page
99).
X Visit a qualified specialist workshop. b
Check Rear Left
Turn Signal

or
Check Rear Right
Turn Signal The rear left-hand or rear right-hand turn signal is faulty.
X Change the bulb (Y page 105).b
Check Front Left
Turn Signal

or
Check Front Right
Turn Signal The front left-hand or front right-hand turn signal is faulty.
X Change the bulb (Y page 105).b
Check Center Brake
Lamp The high-mounted brake lamp is faulty.
X
Visit a qualified specialist workshop.216
Display messages (vehicles with steering wheel buttons)
On-board computer and displays

Display messages
Possible causes/consequences and
M SolutionsVehicles with trailer tow hitch: a fuse may be defective.
X Check the fuses and if necessary replace any blown fuses (see
the "Fuse allocation" supplement).
X If the display message does not disappear, consult a qualified
specialist workshop. b
Check Left Daytime
Running Light or
Check Rt. Daytime
Running Light The left or right-hand daytime running lamp is faulty.
X Change the bulb (Y page 105).218
Display messages (vehicles with steering wheel buttons)
On-board computer and displays

Display messages
Possible causes/consequences and
M SolutionsCruise Control
- - - mph A condition for activating cruise control has not been met.
You have tried to store a speed below
20 mph (30 km/h) for exam-
ple.
X If conditions permit, drive faster than 20 mph (30 km/h) and
store the speed.
X Check the activation conditions for cruise control (Y page
147).Blind Spot Assist
Inoperative Blind Spot Assist is faulty.
X Visit a qualified specialist workshop. Blind Spot Assist
Currently Unavail.
See Operator's Man‐
ual Blind Spot Assist is temporarily inoperative. Possible causes:
R You have attached a trailer.
R The sensors in the rear bumper are dirty.
R The function is impaired due to heavy rain or snow.
R The radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio stations
or other sources of electromagnetic radiation.
R The system is outside the operating temperature range.
Once the causes listed above no longer apply, the display message
goes out and Blind Spot Assist is operational again.
If the display message does not disappear:
X Pull over and stop the vehicle, paying attention to road and traffic
conditions.
X Secure the vehicle to prevent it from rolling away ( Y page
138).
X Switch off the engine.
X Clean the sensors in the rear bumper (Y page
267).
X Restart the engine. Display messages (vehicles with steering wheel buttons)
223
On-board computer and displays Z

Warning/
indicator
lamp
N Signal type
Possible causes/consequences and
M Solutions÷
N The yellow ESP
®
warning lamp is lit while the engine is running.
ESP ®
, BAS, hill start assist, ESP ®
trailer stabilization and Crosswind Assist are
unavailable due to a malfunction.
ATTENTION ASSIST is deactivated and other driving systems could be automati-
cally deactivated.
G WARNING
The brake system continues to function normally, but without the functions lis-
ted above.
The braking distance in an emergency braking situation can thus increase.
If ESP ®
is not operational, ESP ®
will not stabilize the vehicle.
There is an increased risk of skidding and accidents.
X Switch the engine off, wait briefly and start the engine again.
X Check if the display message has disappeared and ESP ®
is operational.
X If the display message continues to be displayed:
R Drive on with care.
R Visit a qualified specialist workshop immediately. Indicator and warning lamps in the instrument cluster
231On-board computer and displays Z

Warning/
indicator
lamp
N Signal type
Possible causes/consequences and
M Solutionså
N The yellow ESP
®
OFF warning lamp is lit while the engine is running or the
ECO start/stop function is activated.
ESP ®
is deactivated. ESP ®
trailer stabilization and Crosswind Assist are deacti-
vated.
G WARNING
If ESP ®
is deactivated, vehicle stabilization assistance is significantly reduced.
There is an increased risk of skidding and accidents.
X Reactivate ESP ®
.
In rare cases , it may be best to deactivate ESP ®
(Y page
68).
X Adapt your driving style to suit the weather and road conditions.
If ESP ®
cannot be activated:
X Drive on with care.
X Have ESP ®
checked at a qualified specialist workshop. 6
N The red restraint system warning lamp is lit while the engine is running.
The restraint system is faulty.
G WARNING
The air bags or Emergency Tensioning Devices may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
There is an increased risk of injury.
X Observe the display messages.
X Drive on with care.
X Have the restraint system and its components checked immediately at a
qualified specialist workshop.
Further information on the restraint system and its components can be found
under "Occupant safety"
(Y page 46).232
Indicator and warning lamps in the instrument cluster
On-board computer and displays