Fuse box diagram Mercedes 203 and relay with designation and location (2024)

1Air conditioner/heater control unit – in the heater control panel2A/C/Heater Fan Control Module – Next to the fan motor3Air purity sensor (air conditioning system)4Sunlight sensor (air conditioning system)5Antenna signal booster – 1, rear window top7Anti-theft control unit (integrated with the multifunctional control unit) – left side of the luggage compartment8Vehicle inclination sensor (anti-theft system) – left side of the luggage compartment9Anti-theft horn – Behind wheel arch trim10Volume change sensors (anti-theft system)11Audio unit – in navigation system12Audio output amplifier (if equipped) – right side of luggage compartment13Additional heater control unit14Auxiliary Heater Remote Control Receiver – Under Dashboard (Rear Luggage Compartment)15Accumulator battery16Brake booster vacuum pump control unit17Central locking signal sensor (infrared) – in the handle of the driver’s door18Diagnostic connector (DLC)19Driver’s door electrical control unit20Left rear door electrical control unit21Passenger door electrical control unit22Control unit for electrical equipment of the right rear door23Fuse/Relay Box, Engine Compartment 124Fuse box/relay dashboard25Fuse/Relay Box, Luggage Compartment26Headlight control unit, left (models with xenon headlights)27Headlight control unit, right (models with xenon headlights)28Sound signals 1/2 – behind the grille29Ignition lock control unit30Electronic immobilizer control unit – (integrated with ignition lock control unit)31Turn signal/alarm relay – in multifunction control box 232Lighting control unit – behind the headlight switch34Multifunction Control Module 1 – Attached to Engine Compartment Fuse/Relay Box – Functions: Interior Lamps, Headlights, Horns, Windshield Wipers, A/C Pressure Control, Headlight Washers, Coolant Level, Brake Fluid Level, Thermometer, Power Actuator door mirrors35Multifunction control unit 2 – connected by fuse / relay box, luggage compartment – functions: Central locking, fuel level, anti-theft system, alarm, rear window defroster, taillights, trunk lid opener, rear window wiper (wagon)36Navigation system control unit37Ambient temperature sensor38Parking system control unit – under the panel, in the rear of the luggage compartment39Rain sensor – upper center windshield40Power seat control unit (with memory), front left – under the seat41Power seat control unit (with memory), front right – under the seat42Seat heating control unit, front – in the switch block43Electronic transmission control unit – sequential manual transmission44Side impact sensor, left – under the rear seat45Side impact sensor, right – under the rear seat46SRS electronic control unit47Steering column electrical control unit – behind the steering wheel48Steering column lock control unit – built into the ignition lock control unit49Sunroof electric control unit50Body height sensor, front (models with xenon headlights) – front anti-roll bar51Body height sensor, rear (models with xenon headlights) – rear axle52Telephone network connection module – under the panel, in the rear of the luggage compartment53Telephone interface control unit – under the panel, in the rear of the luggage compartment54Phone transceiver – under the panel, in the rear of the luggage compartment55Trailer electrical control unit – under the panel, in the rear of the luggage compartment56Electronic gearbox control unit57Shift control unit – automatic transmission selector59Voice activation system unit – under the panel, in the rear of the luggage compartment60Fuse/Relay Box, Engine Compartment 2

2130A Left front door control unit2230A Right front door control unit2315A Cigarette lighter247.5A CD player with changer (in glove compartment)2530A Upper control panel control unit2625A Audio Amplifier2730A Driver’s seat power adjustment control unit (with memory)2830A Spare fuse2930A Driver’s seat power adjustment control unit (with memory)Multifunctional control unit (taxi)3040A Heater air circulation unit3120A EIS control unitIgnition lock control unit3230A Left rear door control unit3330A Right rear door control unit347.5A Terminal 30 socketUntil 31.5.01:Cell phone and D2B transceiver (for built-in phone)Cell phone and transceiver TELE AID D2B (for built-in phone)Phone interface (for optional cell phone)CTEL compensator (for additional cell phone)15A Before 31.3.04: Power passenger seat adjustment control unit (with memory)Until 31.5.03, Taxi: Multifunctional control unitFrom 1.6.03, Taxi: Multifunction control unitFrom 1.6.01, Police: Multifunction control unit30A From 1.4.04: Passenger seat power adjustment control unit (with memory)From 1.4.04, Taxi: Multifunction control unit3530A Until 31.3.04: STH heater unit20A From 1.4.04: STH heater unit3630A Before 31.3.04, Police: Additional equipment power connector15A Engines 612.990 (up to 29.2.04): Charge air cooler circulation pumpFrom 1.4.04, Japan: Audio interface control unit7.5A Universal mobile phone interface3725A Air cooler circulation pumpUp to 29.2.04: Brake booster vacuum pump control unit3830A Up to 29.2.04: Power passenger seat adjustment control unit (with memory)From 1.4.04, Police: Multifunction control unit3930A Spare fuse407.5A Passenger seat power adjustment control unit (with memory)Universal mobile phone interfacecell phone separation pointTelephone interfaceRadiotelephone network compensator EFrom 1.6.01, MB phone: Cell phone and transceiverFrom 1.6.01, TELE AID: Cell phone and transceiverFrom 1.4.04, Japan: E-call control unit30A Up to 31.5.01: Multifunction control unit417.5A Upper control panel control unitUp to 31.5.01: KLA system control panel (Automatic climate control system)15A From 1.6.01: KLA system control panel (Automatic climate control system)427.5A Instrument cluster

43a15A Horn relay43b15A Horn relay445A D2B interfaceTelephone interfaceConnector ferrule 15RTELE AID control unit457.5A SRS control unit4640A Wiper On/Off RelayWiper Mode Relay 1/24715A Glove box lights with sensor-switchFront cigarette lighter (illuminated)4815A Engines 612.990 (up to 31.3.04): Brake booster vacuum pump control unitMotors 112, 113: Fuse-protected connector sleeve 15Engines 646, USA (up to 31.3.04): Fused connector sleeve 30Engines 646 (from 1.4.04): O2 probe before catalytic converter497.5A SRS control unit505A Light switch moduleEngines 612.990Preheating output stage (until 31.3.04)Mass Air Flow Sensor (1.4.04 to 30.11.04)517.5A AAC (automatic A/C) with built-in auxiliary fan electric motorinstrument clusterFor AAS “comfort”:AAC failure sensorSolar radiation sensor AAC (4 pieces)For all vehicles with xenon headlights:Left block headlightRight block headlightAMG: Charge air cooler circulation pump203.0 (until 31.7.01): SRS control unit5215A Starter5325A Diesel engines:Starter relayRear SAM control box with relay and fuse boxEngines 611/612/642/646: CDI control unit15A Gasoline engines:Starter relayRear SAM control box with relay and fuse boxEngines 111/271/272: ME control unitEngines 112/113:ME control unitCable termination electr. circuit terminal 87 M1e5415A Engines 271.940:ME control unitVent valve (USA)Canister shut-off valveEngines 271.942: NOX control unitEngines 642/646: CDI control unitMotors 642/646: Cable termination electr. terminal 30 circuits7.5A Engines 611/612: CDI control unitEngines 611/612 (until 11/30/04): Heating element in the ventilation duct557.5A Steering wheel sensorDistronic: DTR control unitGearbox 722:ETC control unit [EGS] (up to 31.5.04)Selector lever electronic control unitVGS control unitGearbox 716:Sequentronic control unitTransmission Position Sensor565A ESP and BAS control unitBrake light switch575A Steering wheel sensor (up to 31.5.02)Electronic ignition control unit / sensor-switch opening the starter circuitSteering column electronic module (as of 1.6.02)Engines 112/113: ME control unit5840A Transmission 716: Hydraulic pump5950A ESP and BAS control unit6040A ESP and BAS control unit6115A Transmission 716: Sequentronic control unit625A Diagnostic connectorLighting control moduleBrake light switch635A Lighting control module6410A Radio receiverRadio and navigationDisplay and function control unit COMAND6540A Engines 112/113: Electric air pumpRelayIHorn relayKTerminal 87 relay, chassisLWiper Mode Relay 1/2MRelay terminal 15RNKSG pump control relayOAir Pump Relay (Engines 112, 113, 271)PRelay terminal 15QRelay on/off wiperRTerminal 87 relay, motorSStarter relay