Mercedes W251 R-Class was produced in 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 and 2013 in various versions R280, R300, R320, R350, R506. During this period, the model underwent restyling. In this publication, we will provide a description of the fuses and relays of the Mercedes w251 with block diagrams and their locations. We will note the fuse responsible for the cigarette lighter.
The purpose of fuses and relays may differ from the one presented and depends on the year of manufacture and region of delivery of your vehicle.
Blocks in the cabin
Fuse block
On the right side of the instrument panel, behind a protective cover, there is a fuse block.
Description
- 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 2009 model year)
- 16 – Reserve
- 17 – Reserve
- 18 – Reserve
Power fuse block
This unit is located next to the battery under the front passenger seat.
Marking
| 78 | 150A Diesel engines: Additional electric heater |
| 79 | 60A SAM control unit, rear |
| 80 | 60A SAM control unit, rear |
| 81 | 40A Engines 642.870: AdBlue ® system power supply relay |
| Engines 276: Fuse and relay block in the engine compartment | |
| 82 | 150A Before model year 2008: Fuse and relay block in cargo area |
| 100A From model year 2009: Fuse and relay box in cargo area | |
| 83 | 5A Passenger Weight Sensing System (WSS) Control Unit (USA) |
| 84 | 10A Passive safety systems control unit |
| 85 | 25A From 2009 model year: DC/AC transformer control unit (115V outlet) |
| 86 | 30A Fuse block in the front panel |
| 87 | Reserve |
| 88 | 70A Before model year 2008: SAM control unit, front |
| 40A From model year 2009: SAM control unit, front | |
| 89 | 70A SAM control unit, front |
| 90 | 70A SAM control unit, front |
| 91 | 40A Fan Controller |
Blocks under the hood
Fuse and relay block
In the engine compartment, on the right side, there is a main unit with fuses and relays.
Appointment
| 100 | 30A Wiper motor |
| 101 | 15A Electric suction fan for engine and air conditioning with integrated regulator |
| Engines 272, 273: (from 2009 model year) | |
| Switching valve in the closed fuel tank ventilation system | |
| Terminal block for electrical circuits, terminal 87 M1e | |
| Engines 113, 272: (up to 2008 model year) | |
| Regeneration switching valve | |
| Engines 272: (up to 2008 model year) | |
| Interference capacitor 1 audio module | |
| Interference 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 sensor before the catalytic converter | |
| Engines 642.870/872: | |
| O2 sensor before the catalytic converter | |
| 102 | 15A Engines 642, (642.870 until 31.7.10) (from 2009 model year): Transmission oil cooler circulation pump |
| Engines 276: Air cooler circulation pump | |
| Engines 156: Engine oil cooler circulation pump | |
| 103 | 20A Engines 642.950, 642.870/872: CDI control unit |
| Engines 272: ME control unit | |
| Engines 276: | |
| ME control unit | |
| Engine/engine compartment plug connection | |
| 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 | |
| 104 | 15A Engines 272, 273 (from model year 2009): Terminal 87 M2e electrical circuit end cable coupling |
| 272 engines (up to 2008 model year): | |
| Heating system shut-off valve | |
| Intake manifold flap switch valve | |
| Air pump switching valve | |
| Thermostat tri-valve, power steering pump pressure regulator valve | |
| Engines 642.950 (from model year 2009): End cable coupling electrical circuit terminal 87 | |
| Engines 642.870/872 (from model year 2009): Cable end coupling electrical circuit terminals | |
| 642 engines (up to 2008 model year): | |
| Thermal anemometric air mass flow meter of the left bank of cylinders | |
| Thermoanemometric air mass flow meter for the right bank of cylinders | |
| Intake duct shut-off servomotor | |
| End of candle glow time | |
| Heating element in the crankcase ventilation duct | |
| Power steering pump pressure regulator valve | |
| Left exhaust gas recirculation flap servomechanism | |
| Boost pressure control servomechanism | |
| Engines 113: | |
| O2 sensor of the left bank of cylinders before the catalyst | |
| O2 sensor of the right bank of cylinders in front of the catalyst. | |
| O2-left sensor after the catalyst | |
| O2-Right sensor behind the catalyst | |
| Intake manifold switching valve with variable intake tract length | |
| ARF system pressure transducer | |
| Air pump switching valve | |
| 105 | 15A Engines 272, 273 (from 2009 model year): |
| ME control unit | |
| Terminal cable end sleeve for electrical circuits, terminals 87 M1i | |
| 272 engines (up to 2008 model year): | |
| ME control unit | |
| Thermoanemometric air mass flow meter | |
| Left intake camshaft hall sensor | |
| Right intake camshaft Hall sensor | |
| Left exhaust camshaft hall sensor | |
| Right exhaust camshaft hall sensor | |
| 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 | |
| Engine compartment/interior plug connection | |
| Engines 642.870/872: | |
| CDI control unit | |
| Engine compartment/interior plug connection | |
| Terminal cable end sleeve for electrical circuits, terminals 87 | |
| Engines 113: | |
| ME control unit | |
| Interference capacitor 1 radio receiver | |
| Interference suppression capacitor 2 radio receivers | |
| Ignition coil of the 1st cylinder | |
| Ignition coil of the 2nd cylinder | |
| Ignition coil of the 3rd cylinder | |
| Ignition coil of the 4th cylinder | |
| Ignition coil of the 5th cylinder | |
| Ignition coil of the 6th cylinder | |
| Ignition coil of the 7th cylinder | |
| Ignition coil of the 8th cylinder | |
| 106 | Reserve |
| 107 | 40A Engines 113, 272, 273: Electric air pump |
| 108 | 40A Air Compressor Electric Motor |
| 109 | 25A ESP control unit |
| 110 | 10A Alarm siren |
| 111 | 30A DIRECT SELECT automatic transmission servo module |
| 112 | 7.5A Front left headlight unit |
| Front right headlight unit | |
| 113 | 15A Left horn |
| The beep is right. | |
| 114 | 5A SAM front control unit |
| Engines 272 (up to model year 2008): ME control unit | |
| 115 | 5A ESP control unit |
| 116 | 7.5A Electrical control module (VGS) |
| 117 | 7.5A DTR (Distronic) control module |
| 118 | 5A Engines 272, 273, 276: ME control unit |
| 642 engines: CDI control unit | |
| 119 | 5A Engines 642.870/872: CDI control unit |
| 120 | 10A Engines 272, 273, 276 (from 2009 model year): |
| Relay for the electrical circuit of the engine terminal 87 | |
| ME control unit | |
| Engines 113, 272 (up to model year 2008): ME control unit | |
| Engines 642 (from model year 2009): Relay of the electrical circuit of the engine terminal 87 | |
| 642 engines (up to model year 2008): CDI system control unit | |
| 121 | 20A STH heater (autonomous heating system) |
| 122 | 25A Engines 272, 273, 276, 642: Starter |
| 123 | 20A Engines 642: Condensate sensor in fuel filter with heating element |
| Diesel engines from 1.9.08: Condensation sensor in fuel filter with heating element | |
| 124 | 7.5A Electro-hydraulic power steering |
| 125 | Reserve |
| Relay | |
| A | Wiper operation mode relay 1/2 |
| B | Wiper on/off relay |
| C | Engines 156:Coolant circulation pump relay |
| 642 engines (from model year 2009): Coolant circulation pump relay | |
| 642 engines (up to model year 2008): Additional transmission oil cooling circulation pump | |
| D | Relay for the electrical circuit of terminal 87 of the engine |
| AND | Engines 272, 273 (from 2009 model year): Air pump relay |
| Before 2008 model year: Catalyst purge air pump | |
| F | Horn relay |
| G | Air suspension compressor relay |
| H | Relay electrical circuit terminal 15 |
| I | Starter relay |
Power fuse block
This unit is located on the right side of the engine compartment.
Transcript
- 4 – Reserve
- 5 – 40A Valid from 1.7.09: ESP control unit
- 6 – 40A Electro-hydraulic power steering, Valid until 30.6.09: ESP control unit
- 7 – 100A Electric suction fan for engine and air conditioning with integrated regulator
- 8 – 100A Fuse and relay block in the engine compartment
Block in the trunk
The main unit with fuses and relays is located under the trunk floor, behind the soundproofing panel.
Description
| 20 | 5A Radio antenna interference filter |
| Microphone group control unit (Japan; before 2008 model year) | |
| Voice Control System (SBS) Control Unit (USA; before 2008 model year) | |
| 21 | 5A HBF control unit |
| 22 | PTS control unit (parking system) |
| STH remote control receiver (from model year 2009) | |
| 23 | 10A DVD player |
| COMAND control and display unit (from model year 2009) | |
| Radiotelephone network compensator E (since 2009) | |
| Antenna compensator GSM 1800 (up to 2008 model year) | |
| Rear audio control unit (up to 2008 model year) | |
| Control unit (Universal Mobile Phone Interface) (Japan; before 2008 model year) | |
| Mobile phone power circuit connector (Japan; before model year 2008) | |
| 24 | 40A Reversible front right seat belt tensioner |
| 25 | 20A From the 2009 model year: |
| Radio | |
| Radio and navigation system computer | |
| COMAND control and display unit | |
| 15A Before the 2008 model year: | |
| Control panel with COMAND display | |
| Audio system | |
| Audio module and navigation unit | |
| 26 | 25A Front right door control unit |
| 27 | 30A Front seat position adjustment control unit with memory function, front passenger seat |
| Front passenger comfort seat position adjustment relay (up to 2008 model year) | |
| 28 | 30A Front seat position adjustment control unit with memory function, driver’s seat |
| Driver’s seat comfort adjustment relay (up to model year 2008) | |
| 29 | 40A Reversible front left seat belt tensioner |
| 30 | 40A Fuel pump control unit |
| Engines 156: | |
| Left fuel pump control unit | |
| Right fuel pump control unit | |
| 31 | 10A Control unit for seat heating, ventilation and steering wheel heating |
| 32 | 15A AIRMATIC control unit with ADS system |
| Control unit for the body level adjustment system on the rear axle | |
| 33 | 25A KEYLESS-GO system control unit |
| 34 | 25A Front left door control unit |
| 35 | 30A Speaker Amplifier |
| Subwoofer amplifier (from 2009 model year) | |
| 36 | 10A Emergency call system control unit (from 2009 model year) |
| VICS+ETC power supply connector (Japan; before model year 2008) | |
| 5A Emergency call system control unit (up to 2008 model year) | |
| 37 | 5A Rear view camera power supply module |
| Rear view camera control unit | |
| 38 | 10A Digital TV Tuner |
| Combined TV tuner (analog/digital) (Japan) | |
| Audio interface control unit (Japan; before model year 2008) | |
| 39 | 7.5A High-resolution tuner control unit (from 2009 model year) |
| Digital audio broadcasting control unit (from 2009 model year) | |
| RDK control unit (tire pressure monitoring system) | |
| Interface for connecting an external navigation module (South Korea; from 2009 model year) | |
| SDAR control unit (USA; before model year 2008) | |
| 40 | 40A Before model year 2008: Tailgate closing drive control unit |
| 30A From model year 2009: Tailgate closing drive control unit | |
| 41 | 25A Roof control panel control unit |
| 42 | 25A Roof control panel control unit |
| 43 | 20A 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 31.05.2006: | |
| Tailgate wiper motor | |
| Socket 3rd row of seats on the left | |
| Socket for 3rd row of seats on the right | |
| 44 | 20A From the 2009 model year: |
| Socket in the front of the cabin (USA) | |
| 115 V outlet | |
| From 01.06.2006: Not used | |
| Until 31.05.2006: | |
| 2nd row seat outlet on the left | |
| Socket for 2nd row of seats on the right | |
| 45 | 20A Socket 2nd row of seats on the left |
| Socket for 2nd row of seats on the right | |
| Socket in the trunk | |
| Until 31.05.2006: Socket, interior, front | |
| 46 | 15A Cigarette lighter with ashtray illumination, front |
| 47 | 10A Illuminated door sill trim, front left (from model year 2009) |
| Illuminated door sill trim, front right (from 2009 model year) | |
| 48 | 5A Engines 642.870: AdBlue® supply relay |
| 49 | 30A Heated rear window |
| Antenna coil, right (up to 2008 model year) | |
| 50 | 10A Before model year 2008: Tailgate wiper motor |
| 15A From model year 2009: Tailgate wiper motor | |
| 51 | 5A Activated carbon filter shut-off valve |
| 52 | 5A Valid until 30.6.09: |
| Reversible front left seat belt tensioner | |
| Reversible front right seat belt tensioner | |
| 53 | 5A AIRMATIC control unit with ADS system |
| Control unit for the body level adjustment system 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 | |
| 54 | 5A SAM control unit, front |
| Headlight range adjustment control unit | |
| 55 | 7.5A Instrument cluster |
| Outdoor lighting rotary switch | |
| 56 | 5A Engines 642.870: AdBlue ® system control unit |
| Before 2008 model year: Diagnostic connector | |
| 57 | 20A Engines 642.870: Fuel pump |
| Before model year 2008: Fuel pump with fuel level sensor | |
| 58 | 7.5A Diagnostic connector |
| Central interface control unit | |
| 59 | 7.5A NECK-PRO driver’s seat headrest solenoid |
| Front passenger seat NECK-PRO headrest solenoid | |
| 60 | 5A Glove box light with microswitch |
| Fuse and relay block in the engine compartment | |
| Rear SAM control unit | |
| Mobile phone connection interface | |
| Detachable connection of the power supply circuit of the VICS+eTc system (Japan) | |
| Multi-contour seat air pump (from model year 2009) | |
| Emergency call system control unit | |
| Electrical plug connection for the blind spot monitoring system “interior/rear bumper” | |
| 61 | 7.5A Passive safety systems control unit |
| Front right seat contact strip | |
| 62 | 30A Lumbar support control unit, front passenger seat |
| Front passenger seat adjustment switch | |
| 63 | 30A Lumbar support regulator control unit, driver’s seat |
| Driver’s seat adjustment switch | |
| 64 | Reserve |
| 65 | Reserve |
| 66 | 30A Multi-circuit seat air pump (from 2009 model year) |
| 67 | 25A Electric motor of the air conditioning system fan in the rear of the cabin |
| 68 | 25A From model year 2009: Control unit for heating, seat ventilation and steering wheel heating |
| Before model year 2008: Heated rear seats | |
| 69 | Reserve |
| 70 | 20A Towbar socket, 13-pin |
| Towbar socket, 7-pin | |
| 71 | 30A Electronic brake control system connector |
| 72 | 15A Towbar socket, 13-pin |
| Relay | |
| K | Until 31.05.2006: Relay of the electrical circuit of the terminal 15R (Relay of sockets, with a delay of switching off) |
| From 01.06.2006: Relay of the electrical circuit of the terminal 15R of the socket (with a delay in switching off) (power supply of the electric seat adjustment system) | |
| L | Trailer terminal relay 30X |
| M | Tailgate glass heating relay |
| N | Relay electric circuit terminal 15 / terminal 87FW |
| T | Fuel pump relay |
| P | Rear wiper relay |
| R | Relay terminals 15R |
| S | From model year 2009: Reserve 1 (relay with changeover contact) (power supply of the front socket) |
| T | Reserve 2 (relay with closing contact) (power supply to sockets in the center and rear) |
| IN | Relay for electrical circuits terminal 30 (trailer) |
| In | Reserve relay 2 |
Fuse number 46 at 15A is responsible for the front cigarette lighter.