Mercedes W204 is the 3rd generation of C-class cars of the German auto manufacturer Mercedes-Benz, which was produced in 2007, 2008, 2009, 2010, 2011, 2012, 2013 and 2014 with various engine options (C180 cdi, C230, C280, C 300 (4MATIC), C350, C63 AMG, etc.). During this time, the model was restyled. In this material, we will show the locations of electronic control units, a detailed description of fuses and relays of the Mercedes 204 with block diagrams and photo examples of their implementation. We will highlight the fuse responsible for the cigarette lighter.
The location of the blocks and the purpose of the elements in them may differ from that shown and depends on the year of manufacture and the level of electrical equipment of your car.
Location
Control units
General diagram of the location of control units in Mercedes w204
Description
| 1 | Electronic control unit ABS |
| 2 | Electronic air conditioning control unit – in the heater control panel |
| 3 | Air Conditioner/Heater Fan Motor Control Unit – Next to the heater fan motor |
| 4 | Antenna signal amplifier 1 – stand (universal) |
| 5 | Antenna signal amplifier 1 – ceiling panel (sedan) |
| 6 | Antenna signal amplifier 2 – in the rear door (station wagon) |
| 7 | Antenna signal amplifier 2 – pillar “C” (sedan) |
| 8 | Anti-theft alarm siren – behind the wheel arch |
| 9 | Additional battery – under the floor |
| 10 | Auxiliary battery relay – under floor |
| 11 | Battery (Diesel) – under floor |
| 12 | Battery (petrol) |
| 13 | Battery current monitoring relay (combined with fuse box/relay 2 in engine compartment) |
| 14 | Diagnostic Link Connector (DLC) |
| 15 | Control unit for electrical equipment of the left front door |
| 16 | Left rear door electrical equipment control unit |
| 17 | Right front door electrical equipment control unit |
| 18 | Right rear door electrical equipment control unit |
| 19 | Electronic Engine Control Unit (Diesel) – Engine 651 |
| 20 | Electronic Engine Control Unit (Diesel) – except engine 651 |
| 21 | Electronic engine control unit (petrol) |
| 22 | Fuel Pump Control Unit – Engine 271 – Behind Right Trim |
| 23 | Fuel pump control unit – except engine 271 – under the rear right seat |
| 24 | Fuse/Relay Box, Engine Compartment 1 |
| 25 | Engine Compartment Fuse/Relay Box 2 (Fuse Links in Engine Compartment Fuse Box) – Power Circuits: Air Conditioner, Alternator, Auxiliary Battery Relay, Engine Compartment Fuse/Relay Box 1, Engine Control Module, Cooling Fan Motor, Instrument Cluster Fuse/Relay Box, Heater Fan Motor Resistor, Intake Air Heater Heating Element (Diesel), Ignition Switch Control Module, Luggage Compartment Fuse/Relay Box 1, Multifunction Control Module 1/2, Starter, SRS |
| 26 | Fuse/Relay Box, Instrument Panel |
| 27 | Fuse/Relay Box, Luggage Compartment 1 – Behind Right Trim |
| 28 | Fuse/relay box, luggage compartment 2- underfloor |
| 29 | Glow Plug Control Unit |
| 30 | Headlight control unit, left (xenon headlights) |
| 31 | Headlight control unit, right (xenon headlights) |
| 32 | Sound signal 1 – behind the front bumper |
| 33 | Sound signal 2 – behind the front bumper |
| 34 | Ignition switch control unit |
| 35 | Remote central locking and engine start control unit – behind right trim |
| 36 | Lighting control unit |
| 37 | Multifunction Control Unit 1 – Attached to Fuse/Relay Box 1 in Engine Compartment – Functions: Air Conditioning Compressor, Air Conditioning Pressure Monitoring, Brake Fluid Level, Coolant Level, Headlights, Hazard Warning Lights, Headlight Washers, Windshield Washer Nozzle Heaters, Horns, Direction Indicators, Interior Lights, Ambient Air Temperature Sensor, Windshield Wipers |
| 38 | Multifunction control unit 2 – attached to fuse/relay box 1 in the luggage compartment – functions: Anti-theft alarm system, central locking, fuel filler flap/cap, rear window heater, seat heater, tail lights, rear sunblind, (rear door) |
| 39 | Multifunction switch control unit 1 – functions: Front seat heater, parking system, rear window blind, stop-start system, suspension control system |
| 40 | Multifunction switch control unit 2 – functions: Air conditioning, anti-theft system, interior lighting, local lighting, sunroof |
| 41 | Ambient air temperature sensor |
| 42 | Parking system control unit – under the mat |
| 43 | Seat position adjustment memory control unit (left) |
| 44 | Seat position adjustment memory control unit (right) |
| 45 | Steering column electrical equipment control unit – under the steering wheel |
| 46 | Steering Column Lock Control Unit |
| 47 | Electric sunroof drive control unit |
| 49 | Suspension control unit (with active suspension system) – under the mat |
| 50 | Rear door opening/closing drive control unit – D-pillar (station wagon) |
| 51 | Trailer electrical control unit – behind right trim |
| 52 | Electronic control unit of the gearbox (722.6) – under the mat |
| 53 | Electronic control unit of the gearbox (722.9) – in the gearbox |
| 54 | Gear Shift Control Unit – Selector |
| 55 | Tire pressure monitoring system control unit – behind left trim |
Fuse and relay boxes
Scheme
Purpose
- F32 – Front Input Power Fuse Block
- N10/1 – SAM control unit with front relay and fuse module
- N10/2 – SAM control unit with rear relay and fuse module
- F33 – Rear power fuse box
- F34 – Passenger compartment fuse box
Block in the cabin
In the Mercedes 204 cabin, the main fuse box is located at the end of the dashboard, behind a protective cover.
Designation
| 116 | 30A Driver’s seat control unit (before 31.05.09) |
| 117 | 15A Adaptive Damping Control Unit (before 31.05.09) |
| 118 | Reserve |
| 119 | 7,,5A Rear passenger compartment fan motor (up to 31.05.09) |
| AMG Performance Media Control Unit (up to 1.6.12) | |
| 120 | Reserve |
| 121 | Reserve |
| 122 | Reserve |
| 123 | 10A Electronic Steering Column Module Control Unit |
| 124 | Reserve |
| 125 | Reserve |
| 126 | 30A Front passenger seat control unit (before 31.05.09) |
| 127 | Reserve |
| 128 | Reserve |
| 129 | 20A Oil cooler fan motor relay (engine 156; up to 31.05.09) |
| 130 | Reserve |
| 131 | Reserve |
| 132 | Reserve |
| 133 | Reserve |
| 134 | Reserve |
| 135 | Reserve |
Blocks under the hood
Fuse and relay box
The main fuse and relay block under the hood is located on the left side.
Transcript
| 1 | 25A Electronic Stability Program (ESP) Control Unit |
| 2 | 30A Front Left Door Control Unit |
| 3 | 30A Front door control unit, right (up to 31.3.10) |
| 4 | 7.5A Fuel Pump Control Unit (Gasoline Engines) |
| Fuel pump control unit left (engine 156) | |
| Right fuel pump control unit (engine 156) | |
| Fuel filter condensate sensor with heating element (engines 642, 651) | |
| Control unit for condensate sensor in fuel filter with heating element (engines 651 (up to 31.5.10), 646) | |
| 20A Headlight control unit (since 1.3.11) | |
| 5 | 7.5A SAM Control Unit with Rear Fuse and Relay Module |
| Relay for the coolant circulation circuit of the rear axle gearbox (engine 156 from 1.7.11) | |
| Outdoor lighting switch (from 1.12.09) | |
| 6 | 10A CDI Control Unit (Diesel Engines) |
| ME control unit (petrol engines) | |
| 7 | 20A Starter |
| 8 | 7.5A Occupant Restraint System Control Unit |
| 9 | 15A Socket in the Glove Box |
| 10 | 30A Windscreen Wiper Motor |
| 11 | 7.5A Display audio system/ COMAND |
| Audio control panel /COMAND | |
| Holder for navigation module | |
| 12 | 7.5A Climate control system control panel |
| Upper control panel | |
| 13 | 7.5A Electronic Steering Column Module Control Unit |
| Multifunctional camera (since 1.3.11) | |
| 14 | 7.5A Electronic Stability Program (ESP) Control Unit |
| 15 | 7.5A Occupant Restraint System Control Unit |
| Passive safety system control unit | |
| 16 | 5A Diagnostic connector (up to 31.5.09) |
| Electrical plug connection for mobile phone (before 2008) | |
| Electronic selector lever module control unit (KP 722) | |
| 17 | 30A Panoramic sunroof control module with sliding sunroof |
| Ceiling control panel control unit | |
| 18 | 7.5A Outdoor Lighting Switch (before 2008) |
| Control unit of the upper control panel (from 1.3.11) | |
| Terminal sleeve for positive wire of LIN data bus of instrument panel air conditioning system (up to 28.2.11) | |
| Electrical plug connection between the car interior and the wiring harness for the rear side light | |
| 19 | 20A Electric Steering Lock Control Unit |
| Electronic ignition switch control unit | |
| 20 | 40A Electronic Stability Program (ESP) Control Unit |
| 21 | 7.5A Brake Light Sensor |
| Glove box light switch | |
| AKSE front passenger seat occupancy recognition system | |
| Electrical fuse preparation for installation of Electronic Toll Collection system (Japan) | |
| 22 | 15A Electric motor for combustion engine fan and air conditioner with built-in regulation |
| Electrical plug connection of the interior and engine wiring harness | |
| Cable lug electrical circuit terminal 87 M2e (engine 271; South Korea), (engine 272; USA) | |
| ME control unit (engine 271; South Korea) | |
| Regeneration changeover valve (engine 271; South Korea), (engine 272; USA) | |
| CDI system control unit (engines 642, 646) | |
| Heating element in the engine crankcase ventilation duct (engine 642) | |
| Cable lug electrical circuit terminal 87 (engine 646) | |
| 23 | 20A Electrical plug connection for passenger compartment and engine wiring harness |
| SAM control unit with rear fuse and relay module (diesel engines) | |
| CDI system control unit (diesel engines before 2008) | |
| Cable end electrical circuit terminal 87 (diesel engines before 2008) | |
| Cable lug electrical circuit terminal 87 M1e (engine 271 before 2008) | |
| Cable lug electrical circuit terminal 87 M1i (engine 272 before 2008) | |
| 24 | 15A Electrical plug connection for passenger compartment and engine wiring harness |
| Radiator shutter actuator (engine 642) | |
| CDI control unit (engine 646) | |
| Cable lug electrical circuit terminal 87 M1i (engine 272 before 2008) | |
| Cable end electrical circuit terminal 87 (diesel engines before 2008) | |
| 25 | 15A ME Control Unit (engines 156, 271, 272, 274, 276) |
| Lambda probe before catalytic converter (engine 651) | |
| Exhaust system sound generator control unit (engine 651) | |
| 26 | 20A Audio Module |
| Audio module with Auto-Pilot system | |
| COMAND control module | |
| 27 | 7.5A Electronic ignition switch control unit |
| Electric steering lock control unit (before 2008) | |
| CDI control unit (diesel engines) | |
| ME control unit (petrol engines) | |
| 28 | 7.5A Instrument cluster |
| 29 | 10A Front Right Headlight |
| 30 | 10A Front left headlight |
| Electrical plug connection of the interior and engine wiring harness (engine 642) | |
| 31A | 15A Left horn |
| Right horn | |
| 31B | 15A Left horn |
| Right horn | |
| 32 | 40A Electric Air Pump (Motors 156, 271, 272) |
| 33 | 10A Control unit of the electronic control system of automatic transmission (KP 722.6) |
| Control unit for fully integrated automatic transmission control system (KP 722.9) | |
| 34 | 7.5A Fuel pump control unit (engines 274, 276), (engines 271, 272, 651 from 1.6.09), (engine 642 from 1.12.09) |
| 35 | 5A Electronic Stability Program (ESP) control unit (since 2009) |
| 36 | 7.5A Electrical control module DISTRONIC |
| Electro-hydraulic power steering (since 2009) | |
| Relay | |
| J | Relay terminal 15 |
| K | Relay terminal 15R |
| L | Reserve |
| M | Relay terminal 50, starter |
| N | Relay terminal 87, engine |
| THE | Horn relay |
| P | Catalytic converter purge relay |
| Q | Oil Cooler Fan Motor Relay |
| R | Relay terminal 87, chassis |
Power fuse box
It is installed on the right side, next to the rack.
Option 1
Scheme
Description
| 88 | Fuse: |
| Generator | |
| Starter | |
| 88 | 400A Generator (before 2009) |
| 89 | 125A Front SAM Control Unit with Fuse and Relay Module |
| 90 | 40A SAM Control Unit with Rear Fuse and Relay Module |
| 91 | 80A Electric motor for combustion engine fan and air conditioner with built-in regulation |
| 100 | 40A Fan Controller |
| Air conditioning box (before 2009) | |
| 101 | 60A Front SAM Control Unit with Fuse and Relay Module |
| Fuse Holder, Rear Left Door Control Unit (UK) | |
| Fuse Holder, Rear Right Door Control Module (UK) | |
| 102 | Reserve |
| 103 | 150A Additional electric heater (diesel engines) |
| Fuse Holder, Rear Left Door Control Unit (UK) | |
| Fuse Holder, Rear Right Door Control Module (UK) | |
| 104 | 70A Passenger Compartment Fuse Box |
| 105 | 100A Front SAM Control Unit with Fuse and Relay Module |
| 106 | 150A SAM Control Unit with Rear Fuse and Relay Module |
| 107 | Reserve |
| 108 | Reserve |
| 109 | Reserve |
| 110 | Reserve |
Option 2
Scheme for models without “ECO Start-Stop”
Scheme for models with “ECO Start-Stop”
Designation
| 150 | 400A Pyro fuse 88 (without “ECO Start-Stopp”) |
| 200A Generator | |
| Starter | |
| 151 | 100A Electric motor for combustion engine fan and air conditioner with built-in regulation |
| 152 | 150A Front SAM Control Unit with Fuse and Relay Module |
| 153 | 60A Front control unit SAM with fuse and relay module (vehicles with “ECO Start-Stopp”) |
| 154 | 60A Front SAM control unit with fuse and relay module (without “ECO Start-Stopp”) |
| 150A Additional electric heater (vehicles with “ECO Start-Stopp”) | |
| 155 | Reserve |
| 156 | 150A Additional electric heater (without “ECO Start-Stopp”) |
| 100A Front SAM control unit with fuse and relay module (vehicles with “ECO Start-Stopp”) | |
| 157 | 100A Electro-hydraulic power steering |
| Electric Power Steering Control Unit | |
| 158 | 50A Fan controller (without “ECO Start-Stopp”) |
| 150A SAM control unit with rear fuse and relay module (vehicles with “ECO Start-Stopp”) | |
| 159 | 50A Multifunctional control unit for special vehicle (without “ECO Start-Stopp”) |
| 200A Additional battery relay (cars with “ECO Start-Stopp”) | |
| 160 | 60A Passenger compartment fuse box (without “ECO Start-Stopp”) |
| 50A Fan controller (vehicles with “ECO Start-Stopp”) | |
| 161 | 100A Front SAM control unit with fuse and relay module (without “ECO Start-Stopp”) |
| 50A Multifunctional control unit for special vehicle (vehicles with “ECO Start-Stopp”) | |
| 162 | 60A Passenger compartment fuse box (vehicles with “ECO Start-Stopp”) |
| 163 | 150A SAM control unit with rear fuse and relay module (without “ECO Start-Stopp”) |
| 164 | 80A SAM control unit with rear fuse and relay module (without “ECO Start-Stopp”) |
Blocks in the trunk
Fuse and relay box
Installed on the right side behind the side protection.
Purpose
| 37 | 7.5A NECK-PRO Driver Seat Headrest Solenoid Coil |
| 5A NECK-PRO Electromagnet Coil for Front Passenger Seat Headrest | |
| 38 | 15A Tailgate Windscreen Wiper Motor |
| 39 | 30A Rear door control unit left (up to 31.3.10) |
| 40 | Reserve |
| 41 | 30A Right rear door control unit (up to 31.3.10) |
| Front door control unit, right (since 1.4.10) | |
| 42 | 25A Fuel pump control unit (engine 642 from 1.12.09), (engine 651 from 1.6.09) |
| 20A Fuel pump (engine 646)(engine 642 from 11/30/09), (engine 651 from 5/31/09) | |
| 20A Before 2008 model year: | |
| Fuel pump control unit (petrol engines) | |
| Fuel pump (diesel engines) | |
| 43 | 5A Rear passenger compartment fan motor (from 1.6.09) |
| 44 | 30A Front Right Seat Position Adjustment Switch Block |
| Front passenger seat partial electric adjustment switch | |
| 45 | 30A Front Left Seat Position Adjustment Switch Block |
| Driver’s seat semi-electric adjustment switch | |
| 46 | 7.5A Rear Window FM Antenna Amplifier |
| Antenna amplifier FM 2 and DAB | |
| Alarm siren | |
| Interior Protection and Towing Protection Control Unit | |
| Antenna amplifier 1 on the rear window | |
| Antenna amplifier TV 1 and antenna DAB range III | |
| Antenna amplifier TV 2 and KEYLESS-GO | |
| Antenna amplifier KEYLESS-GO | |
| 47 | Reserve |
| 48 | Reserve |
| 49 | 40A Rear Window Defogger |
| 50 | 50A Front Right Reversible Seat Belt Tensioner |
| 51 | 50A Front Left Reversible Seat Belt Tensioner |
| 52 | Reserve |
| 53 | 15/30A Trailer Recognition Control Unit |
| 54 | 7.5A Trailer recognition system control unit (up to 31.5.09) |
| 15A Trailer Recognition Control Unit | |
| 5A Driver’s seat lumbar support and side bolster adjustment switch group (since 2009) | |
| Lumbar support and side bolster adjustment switch group for front passenger seat (since 2009) | |
| AMG valve block front passenger seat (since 2009) | |
| AMG valve block driver’s seat (since 2009) | |
| 55 | 5A AdBlue® control unit ( since 2009) |
| 56 | 15A Trailer Recognition Control Unit |
| Trailer socket (since 2009) | |
| 5A Driver’s seat lumbar support and side bolster adjustment switch group (since 2009) | |
| Lumbar support and side bolster adjustment switch group for front passenger seat (since 2009) | |
| AMG valve block front passenger seat (since 2009) | |
| AMG valve block driver’s seat (since 2009) | |
| 57 | 20A Trailer Recognition Control Unit |
| 58 | 20/30A Trailer Recognition Control Unit |
| 59 | 5A Parking assistance control unit (since 2009) |
| DISTRONIC sensor (DTR) in the front bumper on the left (since 2009) | |
| DISTRONIC sensor (DTR) in the front bumper on the right (since 2009) | |
| Intelligent radar sensor in the rear bumper on the left (since 2009) | |
| Intelligent radar sensor in the rear bumper on the right (since 2009) | |
| 7.5A PARKTRONIC control unit (before 2009) | |
| Radar Sensor Control Unit (before 2009) | |
| 60 | 7.5A Multi-contour seat air pump (since 2009) |
| 61 | 40A Tailgate Drive Control Unit |
| 62 | 30A Driver’s seat control unit (from 1.6.09) |
| 63 | 30A Front passenger seat control unit (from 1.6.09) |
| 64 | 25A AC/DC Converter Control Unit (2009 and up) |
| 65 | 15A Control unit for adaptive damping system (from 1.6.09) |
| Electronic Steering Column Module Control Unit (since 2009) | |
| 66 | 7.5A Gearbox oil circulation pump relay (since 1.6.12) |
| 67 | 30/40A Speaker Amplifier Control Unit |
| 68 | Reserve |
| 69 | 20A Rear Subwoofer Amplifier (2009 and up) |
| 70 | 5A Tire pressure monitoring system control unit |
| 71 | 15A Cigarette Lighter with Front Ashtray Light |
| Socket salon front | |
| 72 | 15A Socket in the Trunk |
| 115 V outlet | |
| 73 | 7.5A Diagnostic connector (from 1.6.09) |
| Driving mode control unit (engine 156 since 1.7.11) | |
| Receiver for remote radio control of autonomous heater (since 2009) | |
| 74 | 15A KEYLESS-GO system control unit |
| 75 | 20A Heating device of independent heater (since 2009) |
| 76 | 15A Interior Socket |
| 77 | 7.5A Weight Sensing System (WSS) Control Unit |
| 78 | 7.5A Front left seat ventilation fan controller (from 1.3.11) |
| Front right seat ventilation fan regulator (from 1.3.11) | |
| 79 | 7.5A Radar Sensor Control Unit (before 2009) |
| 80 | 5A Video and radar sensor control unit (since 2009) |
| Parking assistance system control unit (from 1.6.12) | |
| 81 | 5/7.5A Multimedia Interface Control Unit |
| 82 | 5A UMTS Mobile Compensator (since 2009) |
| TV tuner control unit (before 31.5.09; Japan) | |
| 83 | 7.5A Electronic Toll Collection Control Unit (up to 28.2.11; Japan) |
| Emergency call system control unit | |
| Display in the rear of the cabin on the left (since 2009) | |
| Display in the rear of the cabin on the right (since 2009) | |
| Rear view camera electronics (since 1.6.12; Japan) | |
| 84 | 7.5A Satellite Digital Audio Radio (SDAR) Control Unit |
| SDAR/HD Tuner Control Unit (from 1.6.09 to 31.5.10) | |
| Digital Sound Broadcasting Control Unit | |
| Rear view camera power supply module (up to 31.5.12) | |
| Rear view camera control unit (up to 31.5.12) | |
| Rear view camera electronics (since 1.6.12) | |
| Rear view camera (since 1.6.12) | |
| 360° Camera Control Unit | |
| 85 | 7.5A TV tuner control unit (before 31.5.09; Japan) |
| Digital TV tuner (since 1.6.09; Japan) | |
| 86 | 7.5A DVD Player (since 2009) |
| 87 | 7.5A Emergency Call System Control Unit |
| 88 | 15A Automatic transmission servo module DIRECT SELECT (KP 722) (from 1.6.09) |
| 89 | 20A Trailer detection system control unit (from 1.6.09) |
| Oil cooler fan motor relay (engine 156; from 1.6.09) | |
| Relay for the coolant circulation circuit of the rear axle gearbox (from 1.6.09) | |
| 90 | 40A AdBlue® fuse box (from 1.6.09) |
| AdBlue® supply relay (since 1.6.09) | |
| 91 | Reserve (from 1.6.09) |
| 92 | Reserve (from 1.6.09) |
| Relay | |
| A | Relay terminal 15 |
| B | Relay terminal 15R |
| C | Rear window heating relay |
| D | Fuel pump relay (diesel engines) |
| AND | Trunk Wiper Relay |
| F | Seat Position Adjustment Relay |
| G | Relay terminal 15R |
Fuses 71, 72 and 76 are responsible for the operation of the cigarette lighters.
Power fuse box
Another high power fuse block is attached to the positive terminal on the battery in the trunk.
Scheme
Transcript
| 111 | 60A Front SAM Control Unit with Fuse and Relay Module |
| 112 | 80A Multifunctional Control Unit for Special Vehicle |
| 113 | 40A Fuel pump control unit left (engine 156) |
| Right fuel pump control unit (engine 156) | |
| 114 | Reserve |
| 115 | 100A Multifunctional Control Unit for Special Vehicle |