Table of Contents
The Mercedes-Benz B-Class is a series of compact executive cars produced by the German automaker. First introduced at the 2005 Geneva Motor Show, it was preceded by the Vision B concept car and is manufactured in Rastatt. Below are detailed fuse box diagrams and relay assignments for the second-generation Mercedes-Benz B-Class (chassis code W246 / T242; MPV platform; MFA architecture) for model years 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, and 2019 (B160, B180 CDI, B200, B220 4MATIC, and B250).
Here you will find power distribution box locations and fuse panel assignment diagrams. Fuses responsible for the “Cigarette Lighter” and “Fuel Pump” are highlighted in bold.
In the Engine Compartment
The main power distribution box is located on the left side of the engine compartment. It consists of two sections: the high-current pre-fuse block and the main fuse panel.
High-Current Pre-Fuse Block
Located on the side of the main fuse box.
General view.
| Diagram | ||
|---|---|---|
|
||
| No. | Description | Amps |
| F32k1 | Decoupling relay (F32k1) | |
| F1 | Alternator (300A) / Electric Drive (W242): DC/DC converter control unit (400A) |
300 / 400 |
| F2 | Gasoline models & Electric Drive (W242): Passenger compartment fuse box | 200 |
| Diesel models: Passenger compartment fuse box | 250 | |
| F3 | Electric Power Steering (EPS) control unit | 100 |
| F4 | Signal Acquisition and Actuation Module (SAM control unit) | 40 |
| F5 | Radiator fan motor | 80 |
| F6 | OM607 engine: Fuel heater control unit | 70 |
| F7 | OM607 engine: DPF regeneration auxiliary heater control unit | 125 |
| F8 | OM607, OM651 engines: Glow plug output stage control module | 100 |
Engine Compartment Fuse Panel
Overview photograph.
| Diagram | ||
|---|---|---|
|
||
| No. | Description | Amps |
| J | Horn relay | |
| K | Windshield wiper speed 1/2 relay | |
| L | Windshield wiper ON/OFF relay | |
| M | Starter Terminal 50 relay | |
| Electric Drive (W242): Terminal 87C relay | ||
| N | Terminal 87M relay | |
| O |
|
|
| P | Unassigned | |
| Q |
|
|
| R | Terminal 15 relay | |
| S | Terminal 87 relay | |
| T | Heated windshield relay | |
| 201 | Anti-theft alarm siren | 5 |
| 202 | Auxiliary heater control unit | 20 |
| Electric Drive (W242): Parking lock control unit Terminal 87 relay | 5 | |
| 203 | Right front headlamp control module | 15 |
| Electric Drive (W242): Transmission control unit | 5 | |
| 204 | Electronic Stability Program (ESP) control unit | 25 |
| 205 | Dual horns (left and right) | 15 |
| 206 | OM651 engine: CDI control unit | 5 |
| Electric Drive (W242): Transmission control unit, brake booster vacuum pump relay, electric drive Terminal 87M circuit relay | ||
| 207 | Diesel models: Terminal 87M circuit relay | 5 |
| Electric Drive (W242): High-voltage battery cooling shutoff valve, parking lock control unit | ||
| 208 | M133, OM607 engines: Terminal 87 relay | 7.5 |
| Electric Drive (W242): Radiator fan motor | 5 | |
| 209 | Left front headlamp | 15 |
| Electric Drive (W242): Unassigned | ||
| 210 | Heated windshield relay | 5 |
| From Nov 3, 2014: Starter pre-relay | ||
| 211 | Model 242.848: CNG control unit | 7.5 |
| Electric Drive (W242): Heating circuit coolant circulation pump | 15 | |
| 212 | M133, M270 engines: Terminal 87M3 circuit connector | 15 |
| OM651 engine: EGR cooler bypass switch valve, cooling system vent pipe, thermostat heating element | ||
| OM607 engine: CDI control unit, boost pressure actuator, upstream oxygen (lambda) sensor | ||
| Electric Drive (W242): Electric drive and charger coolant pump | ||
| 213 | M133, M270, OM651 engines: Terminal 87 circuit connector | 15 |
| OM607 engine: Downstream oxygen (lambda) sensor, CDI control unit, metering valve, camshaft Hall-effect sensor | ||
| Electric Drive (W242): Battery cooling circulation pump 1 | ||
| 214 | M133, M270, OM651 engines: Terminal 87 circuit connector | 10 |
| Electric Drive (W242): Battery cooling circulation pump 2 | 15 | |
| 215 | Gasoline engines: Ignition coils (cylinders 1–4) | 20 |
| OM651 engine: Metering valve | ||
| OM607 engine: Metering valve, boost pressure actuator, CDI control unit | ||
| Electric Drive (W242): Thermal management control unit, transmission gateway control unit / high-voltage power distribution unit (from Nov 3, 2014) | 5 | |
| 216 | Gasoline engines: Motor Electronics (ME) control unit | 5 |
| OM607 engine: Transmission control unit | ||
| 217 | 724 transmission: Fully integrated dual-clutch transmission control unit (VGS) | 25 |
| 218 | Electronic Stability Program (ESP) control unit | 5 |
| 219 | Electric Drive (W242): Parking lock control unit | 5 |
| 220 | Transmission oil cooling circulation pump (724 transmission) | 10 |
| 221 | Electric Drive (W242): Brake booster vacuum pump | 40 |
| 222 | Electric Drive (W242): Electric A/C compressor | 7.5 |
| 223 | Unassigned | - |
| 224 | DISTRONIC adaptive cruise control unit | 7.5 |
| COLLISION PREVENTION ASSIST control unit | ||
| 225 | Electric Drive (W242): Transmission control unit | 5 |
| 226 | Model 242.848: CNG control unit | 5 |
| Electric Drive (W242): Power electronics control unit, battery charger control unit | ||
| 227 | Electric Drive (W242): Power electronics control unit | 5 |
| 228 | Electric Drive (W242): Acoustic Vehicle Alerting System (AVAS) | 5 |
| 229 | Left front headlamp | 5 |
| 230 | Electronic Stability Program (ESP) control unit | 5 |
| 231 | Right front headlamp | 5 |
| 232 | Headlamp control module | 15 |
| 233 | Unassigned | - |
| 234 | OM607 engine: Transmission control unit | 5 |
| Electric Drive (W242): High-voltage power distribution unit | 10 | |
| 235 | OM607 engine: Radiator shutter actuator, radiator fan motor | 7.5 |
| M133 engine: Intercooler coolant circulation pump | ||
| 236 | Signal Acquisition and Actuation Module (SAM control unit) | 40 |
| 237 | Electronic Stability Program (ESP) control unit | 40 |
| 238 | Heated windshield | 50 |
| 239 | Windshield wiper speed 1/2 relay | 30 |
| 240A | Starter Terminal 50 relay | 25 |
| Electric Drive (W242): Transmission control unit | 7.5 | |
| 240B | Unfused Terminal 15 relay | 25 |
| 241 | Electric Drive (W242): High-voltage PTC heater module | 7.5 |
In the Passenger Compartment
Located in the front passenger footwell behind the interior trim panel.
General layout of the Mercedes W246 / T242 passenger compartment fuse box.
| Diagram | ||
|---|---|---|
|
||
| No. | Circuit / Component | Amps |
| A | Terminal 15 relay | |
| B | Rear window wiper relay | |
| C | Terminal 15R2 relay | |
| D | Heated rear window relay | |
| E | Terminal 15R1 relay | |
| F | Terminal 30g relay | |
| G | Electric Drive (W242): Terminal 87 relay / Parking lock actuator | |
| 21 | Auxiliary PTC heater (diesel models) | 150 |
| 22 | Auxiliary battery relay (ECO Start/Stop function) | 200 |
| 23 | Front left door control unit | 30 |
| 24 | Front right door control unit | 30 |
| 25 | Signal Acquisition and Actuation Module (SAM control unit) | 30 |
| 26 | Auxiliary battery connector (ECO Start/Stop function) | 10 |
| 27 | Engine compartment fuse and relay box | 30 |
| 28 | Electric Drive (W242): Thermal management control unit | 5 |
| 29 |
|
15 |
| 30 | Trailer recognition control unit | 5 |
| 31 | All-Wheel Drive (4MATIC) control unit | 5 |
| 32 | Steering column module control unit signals | 5 |
| 33 | Audio unit / COMAND system control panel | 5 |
| 34 | Climate control panel (HVAC) | 7.5 |
| 35 | Heated rear window | 40 |
| 36 | Driver seat control unit / Driver seat lumbar support adjustment control unit | 7.5 |
| 37 | Audio unit / COMAND system display | 7.5 |
| 38 | Supplemental Restraint System (SRS / Airbag) control unit | 7.5 |
| 39 | Overhead control panel | 10 |
| 40 | OM651 engine: Transmission control unit | 15 |
| Electric Drive (W242): Transmission control unit | 5 | |
| 41 | Panoramic sliding sunroof control unit | 30 |
| 42 | COMAND control unit / Audio unit | 5 |
| Audio unit | 25 | |
| 43 | PARKTRONIC parking assist control unit | 5 |
| 44 | Front left reversible seat belt tensioner | 40 |
| 45 | Front right reversible seat belt tensioner | 40 |
| 46 | Front passenger seat control unit | 7.5 |
| 47 | Navigation module | 7.5 |
| Adaptive Damping System (ADS) control unit | 25 | |
| 48 | Unassigned | - |
| 49 | Drive Kit Plus control unit for iPhone | 7.5 |
| COMAND cooling fan | 5 | |
| 50 | Reversing camera flap control unit | 5 |
| 51 | Unassigned | - |
| 52 | Parking lock actuator signal | 30 |
| 53 | Unassigned | - |
| 54 | Unassigned | - |
| 55 | KEYLESS-GO control unit, telematics services communication module | 5 |
| 56 | Steering column module control unit signals | 10 |
| 57 | Special-purpose vehicle multifunction control unit | 30 |
| Special-purpose vehicle multifunction control unit | 7.5 | |
| Parking lock actuator motor Terminal 87 relay | 5 | |
| 58 | Special-purpose vehicle fuse box | 30 |
| 59 | Front passenger seat control unit | 30 |
| 60 | Driver seat control unit | 30 |
| 61 | Sound system amplifier control unit | 40 |
| 62 | Electric steering lock control unit (manual transmission 711) | 20 |
| 63 | Fuel pump control unit | 25 |
| Electric Drive (W242): Transmission interface control unit | 5 | |
| 64 | DSRC toll communication control unit, Electronic Toll Collection (ETC) control unit | |
| 65 | Glove compartment light | 5 |
| 66 | Special-purpose vehicle fuse box | 15 |
| Special-purpose vehicle interface | 5 | |
| 67 | Unassigned | - |
| 68 | Unassigned | - |
| 69 | Unassigned | - |
| 70 | Rear cigarette lighter / 12V power socket | 25 |
| 71 | Luggage compartment / trunk 12V power socket | 25 |
| 72 | Front cigarette lighter / 12V power socket with illuminated ashtray | 25 |
| 73 | Electric parking brake control unit | 30 |
| 74 | Electric parking brake control unit | 30 |
| 75 | Trailer recognition control unit | 20 |
| Electric Drive (W242): Battery Management System (BMS) control unit | 5 | |
| 76 | Trailer recognition control unit | 25 |
| Electric Drive (W242): Parking lock control unit | 5 | |
| 77 | Trailer recognition control unit | 25 |
| 78 | Tailgate control unit, special-purpose vehicle fuse box | 40 |
| 79 | Signal Acquisition and Actuation Module (SAM control unit) | 40 |
| 80 | Signal Acquisition and Actuation Module (SAM control unit) | 40 |
| 81 | Climate control blower motor controller | 40 |
| 82 | Overhead control panel | 10 |
| 83 | Electronic Ignition Switch (EIS) control unit | 7.5 |
| 84 | Upper control panel (UCP switch group) | 5 |
| 85 | Anti-theft alarm system (EDW) / tow-away protection / interior motion sensor control unit | 5 |
| 86 | AM/FM antenna amplifier | 5 |
| 87 | Diagnostic link connector (OBD-II) | 10 |
| 88 | Instrument cluster | 10 |
| 89 | Exterior light switch | 5 |
| 90 | Left and right rear bumper radar sensors | 5 |
| 91 | Pedal sensor, footwell light switch | 5 |
| Electric Drive (W242): Battery Management System (BMS) control unit | ||
| 92 | Fuel pump control unit | 5 |
| Electric Drive (W242): Transmission interface control unit | ||
| 93 | Electric parking brake control unit | 5 |
| 94 | Supplemental Restraint System (SRS / Airbag) control unit | 7.5 |
| 95 | Front passenger seat occupancy recognition / Weight Sensing System (WSS) control unit | 7.5 |
| 96 | Rear window wiper motor | 15 |
| 97 | Mobile phone pre-installation connector | 5 |
| 98 | Signal Acquisition and Actuation Module (SAM control unit) | 5 |
| 99 | Tire Pressure Monitoring System (TPMS) control unit | 5 |
| 100 | DIRECT SELECT interface (M133 engine) | 5 |
| 101 | All-Wheel Drive (4MATIC) control unit | 10 |
| 102 | Stationary heater radio remote control receiver | 5 |
| Electric Drive (W242): Transmission control unit | ||
| AMG models (from Sept 1, 2015): DYNAMIC SELECT drive mode control unit | ||
| From June 1, 2016: Telephone and auxiliary heater antenna switch | ||
| 103 | Telematics services communication module, HERMES control unit, emergency call system (eCall) control unit | 5 |
| 104 | Media Interface control unit | 5 |
| 105 | Satellite Digital Audio Radio (SDAR) control unit, Digital Audio Broadcasting (DAB) control unit | 5 |
| Tuner module | 7.5 | |
| 106 | Multifunction camera | 5 |
| 107 | Digital TV tuner | 5 |
| 108 | Reversing camera | 5 |
| Reversing camera (from June 1, 2016) | 7.5 | |
| 109 | Luggage compartment 12V auxiliary power socket | 20 |
| 110 | COMAND control unit, engine sound generator control unit, audio unit | 30 |