Mecedes W251 fuse and relay

Mercedes W251 R-Class was produced in 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 and 2013 in various R280, R300, R320, R350, R500, R550, R63 AMG versions. During this period, the model has been restyled. In this publication, we will present a description of the fuses and relays Mercedes w251 with box diagrams and their locations. Note the fuse responsible for the cigarette lighter.

Mercedes-Benz R-class (W251)

The purpose of the fuses and relays may differ from the one shown and depends on the year of manufacture and the region where your car was delivered.

Passenger compartment

Fuse box

On the right side of the dashboard, behind a protective cover, there is a fuse box.

Location fuse box

Photo for example

Photo 2

Diagram

Diagram

Assignment

  • 10 – 10A Electronic auxiliary fan controller
  • 11 – 5A Instrument cluster
  • 12 – 15A KLA system control panel (Automatic climate control system)
  • 13 – 5A Upper control panel control unit / Steering column module
  • 14 – 7.5A EZS control unit, CD changer (up to 2008 model year)
  • 15 – 5A Electronic compass / multimedia interface control unit (from model year 2009)
  • 16 – Reserve
  • 17 – Reserve
  • 18 – Reserve

Power fuse box

This unit is located next to the battery under the front passenger seat.

location of fuse box mercedes w251

Photo

photo fuse box mercedes 251

Diagram

Diagram

Designation

78150A Diesel engines: Additional electric heater
7960A SAM control unit, rear
8060A SAM control unit, rear
8140A Engines 642.870: AdBlue® power supply relay
Engines 276: Fuse and relay box in the engine compartment
82150A Before MY 2008: Fuse and relay box in cargo area
100A From model year 2009: Fuse and relay box in the cargo area
835A Passenger weight system (WSS) control unit (USA)
8410A Restraint control unit
8525A From model year 2009: DC/AC transformer control unit (115V socket)
8630A Front panel fuse box
87Reserve
8870A Before model year 2008: SAM control unit, front
40A From model year 2009: SAM control unit, front
8970A SAM control unit, front
9070A SAM control unit, front
9140A Fan regulator

Engine compartment

Fuse and relay box

In the engine compartment, on the right side, is the main fuse and relay box.

Photo fuse box mercedes w251

Diagram

Diagram

Allocation

10030A Wiper motor
10115A Suction motor and air conditioning fan with integrated regulator
Engines 272, 273: (from model year 2009)
Change-over valve in the closed ventilation system of the fuel tank
Cable termination electr. circuit terminal 87 M1e
Engines 113, 272: (up to MY 2008)
Regeneration change-over valve
272 engines: (up to MY 2008)
Noise suppression capacitor 1 audio module
Noise suppression capacitor 2 audio modules
Cylinder 1 ignition coil
Cylinder 2 ignition coil
Cylinder 3 ignition coil
Cylinder 4 ignition coil
Cylinder 5 ignition coil
Cylinder 6 ignition coil
Engines 642:
CDI control unit
O2 probe before catalytic converter
Engines 642.870/872:
O2 probe before catalytic converter
10215A Engines 642, (642.870 to 31.7.10) (from model year 2009): Gearbox oil cooler circulation pump
276 Engines: Charge Air Cooler Circulation Pump
Engines 156: Engine oil cooler circulation pump
10320A Engines 642.950, 642.870/872: CDI control unit
Engines 272: ME control unit
Engines 276:
ME control unit
Plug connection engine/engine compartment
25A Engines 113:
ME control unit
Fuel injector 1st cylinder
Fuel injector 2nd cylinder
Fuel injector 3rd cylinder
Fuel injector 4th cylinder
Fuel injector 5th cylinder
Fuel injector 6th cylinder
Fuel injector 7th cylinder
Fuel injector 8th cylinder
642 engines (up to model year 2008): CDI system control unit
10415A Engines 272, 273 (from model year 2009): Cable termination electr. circuit terminal 87 M2e
Engines 272 (before MY 2008):
Heating shut-off valve
Changeover flap valve in the intake manifold
Air pump changeover valve
Three-plate thermostat valve Power steering pump pressure regulator valve
Engines 642.950 (from model year 2009): Cable termination electr. terminal 87 circuits
Engines 642.870/872 (from model year 2009): Cable termination electr. circuit terminals
642 engines (up to MY 2008):
Hot-film air mass meter for the left cylinder bank
Hot-film mass air flow meter of the right row of cylinders
Inlet duct cut-off servomotor
End of candle glow time
Heating element in crankcase ventilation duct
Power Steering Pump Pressure Control Valve
Servomechanism for left exhaust gas recirculation flap
Boost pressure control servo
Engines 113:
Left O2 sensor before catalytic converter
Right O2 sensor before catalytic converter
O2-Left sensor behind catalytic converter
O2-Right sensor behind catalytic converter
Variable intake manifold changeover valve
ARF System Pressure Transmitter
Air pump changeover valve
10515A Engines 272, 273 (from model year 2009):
ME control unit
Cable termination electr. circuit terminal 87 M1i
Engines 272 (up to model year 2008):
ME control unit
hot-wire air mass meter
Left intake camshaft hall sensor
Right intake camshaft hall sensor
Left hall sensor, left exhaust camshaft
Hall sensor, right exhaust camshaft
Left intake camshaft control solenoid
Right intake camshaft control solenoid
Left exhaust camshaft control solenoid
Right intake camshaft control solenoid
Fuel injector 1st cylinder
Fuel injector 2nd cylinder
Fuel injector 3rd cylinder
Fuel injector 4th cylinder
Fuel injector 5th cylinder
Fuel injector 6th cylinder
Engines 276: Engine/engine compartment plug connection
642 engines (up to model year 2008): CDI control unit
Engines 642.950:
CDI control unit
Plug connection engine compartment/interior
Engines 642.870/872:
CDI control unit
Plug connection engine compartment/interior
Cable termination electr. terminal 87 circuits
Engines 113:
ME control unit
Interference suppression capacitor 1 radio receiver
Interference suppression capacitor 2 radios
Ignition coil 1st cylinder
Ignition coil 2nd cylinder
3rd cylinder ignition coil
4th cylinder ignition coil
Ignition coil 5th cylinder
Ignition coil of the 6th cylinder
Ignition coil of the 7th cylinder
Ignition coil of the 8th cylinder
106Reserve
10740A Engines 113, 272, 273: Electric air pump
10840A Air compressor motor
10925A ESP control unit
11010A Alarm Siren
11130A Servo drive module, automatic transmission DIRECT SELECT
1127,5A Front left headlight
Block headlight front right
11315A Horn left
Sound signal right
1145A SAM control unit, front
Engines 272 (up to model year 2008): ME control unit
1155A ESP control unit
1167.5A Electrical control module (VGS)
1177.5A DTR control module (Distronic)
1185A Engines 272, 273, 276: ME control unit
642 engines: CDI control unit
1195A Engines 642.870/872: CDI control unit
12010A Engines 272, 273, 276 (from model year 2009):
Relay el. motor terminal 87 circuit
ME control unit
Engines 113, 272 (up to model year 2008): ME control unit
Engines 642 (since 2009 model year): Relay el. motor terminal 87 circuit
642 engines (up to model year 2008): CDI system control unit
12120A Heater STH (auxiliary heating system)
12225A Engines 272, 273, 276, 642: Starter
12320A Engines 642: Fuel filter condensation sensor with heating element
Diesel engines from 1.9.08: Fuel filter condensation sensor with heating element
1247.5A Electro-hydraulic power steering
125Reserve
Relay
АWiper Mode Relay 1/2
BRelay on/off wiper
CEngines 156: Coolant circulation pump relay
642 engines (from model year 2009): Coolant circulation pump relay
642 engines (up to model year 2008): Additional circulation pump for gearbox oil cooling
DRelay, electr. motor terminal 87 circuit
EEngines 272, 273 (since MY 2009): Air pump relay
Before MY 2008: Catalyst Purge Air Pump
FHorn relay
GAir Suspension Compressor Relay
HRelay, electr. terminal 15 circuits
IStarter relay

For the front cigarette lighter, fuse number 46 at 15A is responsible.

Power fuse box

This box is located on the right side of the engine compartment.

location

Diagram

Diagram f

Appointment

  • 4 – Reserve
  • 5 – 40A Valid from 1.7.09: ESP control unit
  • 6 – 40A Electro-hydraulic power steering, Valid until 6/30/09: ESP control unit
  • 7 – 100A Suction fan for engine and air conditioner with integrated regulator
  • 8 – 100A Fuse and relay box in the engine compartment

Luggage compartment

The main unit with fuses and relays is located under the boot floor, behind the soundproof lining.

Photo fuse box 251

Diagram

Diagram 5

Decoding

205A Radio Antenna Noise Filter
Mic group control box (Japan; before MY 2008)
Voice Control System (SBS) control unit (USA; before MY 2008)
215A HBF control unit
22PTS control unit (parktronic)
Remote control receiver STH (from model year 2009)
2310A DVD player
COMAND control and display unit (from model year 2009)
Radiotelephone network compensator E (from model year 2009)
Antenna compensator GSM 1800 (up to model year 2008)
Rear audio control unit (before model year 2008)
Control Unit (Universal Mobile Phone Interface) (Japan; before MY 2008)
Electrical connector mobile phone chains (Japan; before MY 2008)
2440A Front right seat belt reversible pretensioner
2520A From model year 2009:
Radio
Radio receiver and navigation computer
Block-panel for control and indication COMAND
15A Before MY 2008:
Control panel with COMAND system display
Audio system
Audio module and navigation unit
2625A Front right door control unit
2730A Front seat adjustment control unit with memory function, front passenger seat
Comfort Relay, Passenger Seat Adjustment (up to MY 2008)
2830A Front seat adjustment control unit with memory function, driver’s seat
Driver’s seat comfort relay (before 2008)
2940A Front left seat belt reversible pretensioner
3040A Fuel pump control unit
Engines 156:
Left fuel pump control unit
Right fuel pump control unit
3110A Control unit for heating, seat ventilation and steering wheel heating
3215A AIRMATIC control unit with ADS system
Control unit for body level control on the rear axle
3325A KEYLESS-GO system control unit
3425A Front left door control unit
3530A Speaker Amplifier
Subwoofer amplifier (since MY 2009)
3610A Emergency call system control unit (from model year 2009)
Detachable power supply VICS+ETC connection (Japan; before MY 2008)
5A Emergency call system control unit (before model year 2008)
375A Rear view camera power supply module
Rear view camera control unit
3810A Digital TV Tuner
Combo TV tuner (analogue/digital) (Japan)
Audio interface control unit (Japan; before MY 2008)
397.5A High definition tuner control unit (from model year 2009)
Digital audio broadcasting control unit (as of model year 2009)
RDK control unit (tire pressure monitoring system)
Interface for connecting an external navigation module (South Korea; from model year 2009)
SDAR control unit (US; before MY 2008)
4040A Before MY 2008: Tailgate close actuator control unit
30A From model year 2009: Tailgate close actuator control unit
4125A Roof control panel control unit
4225A Roof control panel control unit
4320A Engines 272, 273, 276: Fuel pump control unit (from model year 2009)
Engines 642.872: Right fuel pump control unit (from model year 2009)
Until 05/31/2006:
Tailgate wiper motor
Socket 3 row seats left
Power outlet 3rd row right
4420A From model year 2009:
Socket in the front of the cabin (USA)
Socket 115 V
From 06/01/2006: Not used
Until 05/31/2006:
Socket 2nd row of seats on the left
Socket 2nd row right
4520A Socket, 2nd seat row, left
Socket 2nd row right
Socket in the trunk
Up to 05/31/2006: Interior socket front
4615A Cigarette lighter with ashtray light, front
4710A Illuminated treadplate, front left (from model year 2009)
Illuminated treadplate, front right (as of model year 2009)
485A Engines 642.870: AdBlue® relay
4930A Heated rear window
Antenna Coil, Right (Before MY 2008)
5010A Before MY 2008: Tailgate wiper motor
15A From model year 2009: Tailgate wiper motor
515A Activated carbon filter stop valve
525A Valid until 30.6.09:
Reversible front left seat belt pretensioner
Reversible front right seat belt pretensioner
535A AIRMATIC control unit with ADS system
Control unit for body level control on the rear axle
Engines 272, 273, 276: Fuel pump control unit
Engines 642.872: Right fuel pump control unit
Engines 156:
Left fuel pump control unit
Right fuel pump control unit
545A SAM control unit, front
Headlight beam throw control unit
557.5A Instrument cluster
Rotary switch outdoor lighting
565A Engines 642.870: AdBlue® control unit
Before MY 2008: Diagnostic connector
5720A Engines 642.870: Fuel pump
Before MY 2008: Fuel pump with fuel gauge
587.5A Diagnostic connector
Central interface control unit
597,5A Driver seat NECK-PRO headrest solenoid
NECK-PRO Headrest Solenoid, Passenger Seat
605A Glove box light with microswitch
Fuse and relay box in the engine compartment
Rear SAM control unit
Mobile phone interface
Detachable connection of the power supply circuit of the VICS + eTc system (Japan)
Air pump for multi-contour seat (as of model year 2009)
Emergency call system control unit
Blind spot monitoring system “interior/rear bumper” electrical connector
617.5A Restraint control unit
Contact strip front right seat
6230A Lumbar support adjuster control unit, front passenger seat
Front passenger seat adjustment switch
6330A Lumbar support adjuster control unit, driver’s seat
Driver seat adjustment switch
64Reserve
65Reserve
6630A Air pump for multi-contour seat (from model year 2009)
6725A Climate system blower motor in the rear
6825A From model year 2009: Control unit for heating, seat ventilation and steering wheel heating
Before MY 2008: Heated rear seats
69Reserve
7020A Drawbar socket, 13-pin
Drawbar socket, 7-pin
7130A Brake electronic control connector
7215A Drawbar socket, 13-pin
Relay
KBefore 05/31/2006: Terminal 15R Electrical Circuit Relay (Socket Relay, OFF-Delay)
From 06/01/2006: Electrical circuit relay socket terminal 15R (off-delay) (electrical seat adjustment power supply)
LRelay terminal 30X trailer
МHeated rear window relay
NRelay el. circuit terminal 15 / terminal 87FW
OFuel pump relay
PRear Wiper Relay
RRelay terminal 15R
SFrom model year 2009: Reserve 1 (changeover relay) (front socket power supply)
TReserve 2 (NC relay) (power supply for outlets in center and rear)
URelay el. terminal 30 circuits (trailer)
VReserve relay 2

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