Mercedes 203 C-class represents the second generation of the model range, which was produced in 2000, 2001, 2002, 2003, 2004, 2005, 2006 and 2007 with bodies sedan w203, station wagon s203, coupe (C160, C180, C230, C240, C280, C320). During this time, the model has undergone restyling. In this publication you will find information about the location of electronic control units, a detailed description of fuses and relays Mercedes 203 with block diagrams and photo examples of their location. We note the fuses responsible for the cigarette lighter and fuel pump.
The location of the blocks and the design of the elements in them may differ from the one presented and depends on the year of manufacture, region of delivery and level of electrical equipment of your car.
Arrangement
| № | Description |
|---|---|
| 1 | Air conditioning/heater control unit – in the heater control panel |
| 2 | Air conditioner/heater fan control unit – next to the fan motor |
| 3 | Air quality sensor (air conditioning system) |
| 4 | Sunlight sensor (air conditioning system) |
| 5 | Antenna signal amplifier – 1, upper part of the rear window |
| 7 | Anti-theft system control unit (combined with multi-function control unit) – left side of luggage compartment |
| 8 | Vehicle tilt sensor (anti-theft system) – left side of the luggage compartment |
| 9 | Anti-theft alarm sound – behind the wheel arch trim |
| 10 | Volume change sensors (anti-theft system) |
| 11 | Audio system unit – in the navigation system |
| 12 | Audio output amplifier (if equipped) – right side of luggage compartment |
| 13 | Auxiliary heater control unit |
| 14 | Auxiliary heater remote control receiver – under the panel (rear of the luggage compartment) |
| 15 | Rechargeable battery |
| 16 | Brake booster vacuum pump control unit |
| 17 | Central locking signal sensor (infrared) – in the driver’s door handle |
| 18 | Diagnostic Connector (DLC) |
| 19 | Driver’s door electrical control unit |
| 20 | Left rear door electrical control unit |
| 21 | Passenger door electrical control unit |
| 22 | Right rear door electrical control unit |
| 23 | Fuse/relay block, engine compartment 1 |
| 24 | Fuse/relay block dashboard |
| 25 | Fuse/relay block, luggage compartment |
| 26 | Headlight control unit, left (models with xenon headlights) |
| 27 | Headlight control unit, right (models with xenon headlights) |
| 28 | Audible signals 1/2 – behind the radiator grille |
| 29 | Ignition lock control unit |
| 30 | Electronic immobilizer control unit – (combined with the ignition lock control unit) |
| 31 | Turn signal/hazard alarm relay – in multifunction control unit 2 |
| 32 | Lighting control unit – behind the headlight switch |
| 34 | Multifunction control unit 1 – attached to the fuse/relay box in the engine compartment – functions: Interior lights, main lights, horn, windshield wipers, air conditioning pressure control, headlight washers, coolant level, brake fluid level, thermometer, electric door mirrors |
| 35 | Multifunction control unit 2 – connected by fuse/relay block, luggage compartment – functions: Central locking, fuel level, anti-theft system, alarm, rear window heater, tail lights, trunk lid opening drive, rear window wiper (wagon) |
| 36 | Navigation system control unit |
| 37 | Ambient temperature sensor |
| 38 | Parking system control unit – under the panel, in the rear of the luggage compartment |
| 39 | Rain sensor – upper center of windshield |
| 40 | Electric seat control unit (with memory), front left – under the seat |
| 41 | Electric seat control unit (with memory), front right – under the seat |
| 42 | Seat heating control unit, front – in the switch block |
| 43 | Electronic gearbox control unit – sequential manual transmission |
| 44 | Side impact sensor, left – under the rear seat |
| 45 | Side impact sensor, right – under the rear seat |
| 46 | SRS electronic control unit |
| 47 | Steering column electrical control unit – behind the steering wheel |
| 48 | Steering column lock control unit – built into the ignition lock control unit |
| 49 | Electric sunroof control unit |
| 50 | Body height sensor, front (models with xenon headlights) – front anti-roll bar |
| 51 | Body height sensor, rear (models with xenon headlights) – rear axle |
| 52 | Telephone network connection module – under the panel, in the rear of the luggage compartment |
| 53 | Telephone interface control unit – under the panel, in the rear of the luggage compartment |
| 54 | Telephone receiver – under the panel, in the rear of the luggage compartment |
| 55 | Trailer electrical control unit – under the panel, in the rear of the luggage compartment |
| 56 | Electronic gearbox control unit |
| 57 | Gear shift control unit – automatic transmission selector |
| 59 | Voice activation system unit – under the panel, in the rear of the luggage compartment |
| 60 | Fuse/relay block, engine compartment 2 |
| № | Marking |
|---|---|
| F32 | Power fuse block |
| F34 | Fuse box in the instrument panel |
| N10/1 | Fuse and relay block in the engine compartment |
| N10/2 | Fuse and relay block in the luggage compartment |
Cabin block
In the cabin, the fuse box is located on the left side of the dashboard behind a protective cover.
| № | A | Appointment |
|---|---|---|
| 21 | 30 | Left front door control unit |
| 22 | 30 | Right front door control unit |
| 23 | 15 | Cigarette lighter |
| 24 | 7,5 | CD player with changer (in the glove compartment) |
| 25 | 30 | Upper control panel control unit |
| 26 | 25 | Sound amplifier |
| 27 | 30 | Driver’s seat electric adjustment control unit (with memory) |
| 28 | 30 | Spare fuse |
| 29 | 30 | Driver’s seat electric adjustment control unit (with memory) |
| Multifunction control unit (taxi) | ||
| 30 | 40 | Heater air circulation unit |
| 31 | 20 | EIS control unit |
| Ignition lock control unit | ||
| 32 | 30 | Left rear door control unit |
| 33 | 30 | Right rear door control unit |
| 34 | 7,5 | Terminal connector coupling 30 |
| Until 31.5.01: | ||
| Cell phone and D2B receiver (for built-in phone) | ||
| Cellular phone and receiver TELE AID D2B (for built-in phone) | ||
| Telephone interface (for optional cell phone) | ||
| CTEL compensator (for additional cell phone) | ||
| 15 | Until 31.3.04: Passenger seat electric adjustment control unit (with memory) | |
| Until 31.5.03, Taxi: Multifunctional control unit | ||
| From 1.6.03, Taxi: Multifunctional control unit | ||
| From 1.6.01, Police: Multifunctional control unit | ||
| 30 | From 1.4.04: Passenger seat electric adjustment control unit (with memory) | |
| From 1.4.04, Taxi: Multifunctional control unit | ||
| 35 | 30 | Until 31.3.04: STH heater unit |
| 20 | From 1.4.04: STH heater unit | |
| 36 | 30 | Until 31.3.04, Police: Power connector for additional equipment |
| 15 | Engines 612.990 (until 29.2.04): Charge air cooler circulation pump | |
| From 1.4.04, Japan: Audio Interface Control Unit | ||
| 7,5 | Universal mobile phone interface | |
| 37 | 25 | Charge air cooler circulation pump |
| Before 29.2.04: Brake booster vacuum pump control unit | ||
| 38 | 30 | Until 29.2.04: Passenger seat electric adjustment control unit (with memory) |
| From 1.4.04, Police: Multifunctional control unit | ||
| 39 | 30 | Spare fuse |
| 40 | 7,5 | Passenger seat electric adjustment control unit (with memory) |
| Universal mobile phone interface | ||
| Mobile phone separation point | ||
| Telephone interface | ||
| Radiotelephone network compensator E | ||
| From 1.6.01, MB phone: Cellular phone and transceiver | ||
| From 1.6.01, TELE AID: Cellular phone and transceiver | ||
| From 1.4.04, Japan: E-call control unit | ||
| 30 | Until 31.5.01: Multifunctional control unit | |
| 41 | 7,5 | Upper control panel control unit |
| Until 31.5.01: KLA system control panel (Automatic climate control system) | ||
| 15 | From 1.6.01: KLA system control panel (Automatic climate control system) | |
| 42 | 7,5 | Instrument combination |
In the Mercedes 203, fuse 23 is responsible for the cigarette lighter. Another fuse is located in the block under the hood or luggage compartment (USA).
Block under the hood
Main unit
Under the hood in the engine compartment on the left side, under a protective cover, is a fuse and relay block.
| № | A | Appointment |
|---|---|---|
| 43a | 15 | Horn relay |
| 43b | 15 | Horn relay |
| 44 | 5 | D2B interface |
| Telephone interface | ||
| 15R connector coupling | ||
| TELE AID control unit | ||
| 45 | 7,5 | cSRS control unit |
| 46 | 40 | Wiper on/off relay |
| Wiper operation mode relay 1/2 | ||
| 47 | 15 | Glove box lighting with sensor – switch |
| Front cigarette lighter (with light) | ||
| 48 | 15 | Engines 612.990 (until 31.3.04): Brake booster vacuum pump control unit |
| Engines 112, 113: Fused connector coupling 15 | ||
| 646 Engines, USA (until 3/31/04): Fused connector coupler 30 | ||
| Engines 646 (from 1.4.04): O2 probe before the catalytic converter | ||
| 49 | 7,5 | SRS control unit |
| 50 | 5 | Light switch module |
| Engines 612,990 | ||
| Output stage of pre-heating (until 31.3.04) | ||
| Mass air flow sensor (1.4.04 to 30.11.04) | ||
| 51 | 7,5 | AAC (automatic air conditioning) with built-in electric motor for additional fan |
| Instrument combination | ||
| For AAS “comfort”: | ||
| AAC failure sensor | ||
| AAS solar radiation sensor (4 pieces) | ||
| For all vehicles with xenon headlights: | ||
| Left headlight | ||
| Rights block headlight | ||
| AMG: Charge air cooler circulation pump | ||
| 203.0 (until 31.7.01): SRS control unit | ||
| 52 | 15 | Starter |
| 53 | 25 | Diesel engines: |
| Starter relay | ||
| Rear SAM control unit with relay and fuse box | ||
| Engines 611/612/642/646: CDI control unit | ||
| 15 | Gasoline engines: | |
| Starter relay | ||
| Rear SAM control unit with relay and fuse box | ||
| Engines 111/271/272: ME control unit | ||
| Engines 112/113: | ||
| ME control unit | ||
| Terminal 87 M1e electrical circuit cable end sleeve | ||
| 54 | 15 | Engines 271.940: |
| ME control unit | ||
| Ventilation valve (USA) | ||
| Coal adsorber shut-off valve | ||
| Engines 271.942: NOX control unit | ||
| 642/646 engines: CDI control unit | ||
| Engines 642/646: Terminal 30 electrical circuit cable end sleeve | ||
| 7,5 | Engines 611/612: CDI control unit | |
| Engines 611/612 (until 30.11.04): Heating element in the ventilation duct | ||
| 55 | 7,5 | Steering wheel rotation sensor |
| Distronic: DTR control unit | ||
| Gearbox 722: | ||
| ETC control unit [EGS] (until 31.5.04) | ||
| Electronic selector lever control unit | ||
| VGS control unit | ||
| Gearbox 716: | ||
| Sequentronic control unit | ||
| Transmission position sensor switch | ||
| 56 | 5 | ESP and BAS control unit |
| Brake light switch sensor | ||
| 57 | 5 | Steering wheel rotation sensor (until 31.5.02) |
| Electronic ignition/brake light starter circuit open sensor switch control unit | ||
| Electronic steering column module (from 1.6.02) | ||
| Engines 112/113: ME control unit | ||
| 58 | 40 | Transmission 716: Hydraulic pump |
| 59 | 50 | ESP and BAS control unit |
| 60 | 40 | ESP and BAS control unit |
| 61 | 15 | Transmission 716: Sequentronic control unit |
| 62 | 5 | Diagnostic connector |
| Lighting control module | ||
| Brake light switch sensor | ||
| 63 | 5 | Lighting control module |
| 64 | 10 | Radio |
| Radio and navigation | ||
| Display and control unit for COMAND operation | ||
| 65 | 40 | Engines 112/113: Electric air pump |
| Relay | ||
| I | Horn relay | |
| K | Relay terminal 87, chassis | |
| L | Wiper operation mode relay 1/2 | |
| M | Relay terminals 15R | |
| N | KSG pump control relay | |
| THE | Air pump relay (engines 112, 113, 271) | |
| P | Relay terminals 15 | |
| Q | Wiper on/off relay | |
| R | Relay terminal 87, engine | |
| S | Starter relay | |
Power unit
An additional high-power fuse block in the form of fuse links is installed next to the battery.
| № | A | Description |
|---|---|---|
| 1 | 125 | Fuse box in the instrument panel |
| 2 | 200 | SAM control unit, rear |
| 3 | 125 | Additional fuse block |
| 4 | 200 | SAM control unit, front |
| 5 | 125 | Electric suction fan for engine and air conditioning with integrated regulator Diesel engines: Preheating output stage |
| 6 | 60 | SAM control unit, front |
Block in the trunk
It is located in the luggage compartment behind the trim.
| № | A | Marking |
|---|---|---|
| 1 | 30 | Front right seat position adjustment switch block |
| Front passenger partially electric seat adjustment switch | ||
| 2 | 30 | Front left seat position adjustment switch block |
| Driver’s seat partially electrically adjustable switch | ||
| 3 | 7,5 | Interior lighting |
| Trunk lighting | ||
| Remote control receiver | ||
| Tire pressure management | ||
| 20 | TV tuner | |
| 4 | 20 | Fuel pump relay |
| 5 | 20 | Engines 112.961 (until 31.3.04): Charge air cooler circulation pump |
| Except 112.961: Backup relay 2 | ||
| 6 | 25 | Spare fuse |
| 7 | 7,5 | Backup relay 1 |
| 8 | 7,5 | Rear window antenna amplifier module |
| Alarm siren | ||
| ATA tilt sensor | ||
| 9 | 25 | Ceiling control panel control unit |
| 10 | 40 | Rear window heater |
| 11 | 20 | Spare fuse |
| 12 | 15 | Optional equipment power connector |
| 203.0 – USA (until 31.3.04): Socket | ||
| 13 | 5 | Multi-circuit seat air pump |
| Voice Control System (VCS) – Voice Control Unit | ||
| Motorola Star TAC Cell Phone, retrofit – D2B Interface for Portable Cell Phone | ||
| Rear reading light | ||
| PTS (parking system) signal display | ||
| PTS control unit (parking system) | ||
| 14 | 15 | Rear stack wiper |
| 15 | 10 | Filler relay, polarity receiver |
| 16 | 20 | For VSC: Voice control unit |
| For CTEL Motorola Star TAC, retrofit: D2B interface for mobile phone | ||
| 17 | 20 | Trailer electrical control unit |
| 18 | 20 | Towbar socket, 13-pin |
| 19 | 20 | Multi-circuit seat air pump |
| 20 | 15 | Rear window tinting |
| 203.2/7 – USA: Outlet | ||
| Relay | ||
| A | Fuel pump relay | |
| B | Relay 2, terminal 15R | |
| C | Backup relay 2 | |
| D | Backup relay 1 | |
| E | Rear window heater relay | |
| F | Relay 1, terminal 15R | |
| G | Filler relay, polarity switch 1 | |
| H | Filler relay, polarity switch 2 | |