The Mercedes-Benz B-Class is a compact car produced by the German automaker. First introduced at the 2005 Geneva Motor Show, it was preceded by the Vision B concept car and manufactured in Rastatt, Germany. This article provides detailed fuse box diagrams and relay locations for the first-generation Mercedes-Benz B-Class (W245 chassis; models B160, B170, B180, B200) produced from 2005 to 2012.
Below you will find fuse box locations, photos, and circuit assignments. Fuses for the “Cigarette lighter” and “Fuel pump” are highlighted in bold.
Passenger Compartment
The passenger compartment contains two main distribution boxes responsible for protecting electrical circuits.
Fuse Box
Located in the front passenger footwell. Access it by removing the floor panel.
General view of the Mercedes-Benz B-Class (W245) interior fuse box.
| Diagram | ||
|---|---|---|
|
||
| No. | A | Description |
| 1 | 10 | 2005–2008: Brake light switch |
| 5 | 2008–2012 & 2005–2008 with code U58: Brake light switch | |
| 2 | 25 | Heated rear window |
| 3 | 7.5 | Instrument cluster |
| Electronic Ignition Switch (EZS) control unit | ||
| 4 | 15 | Electronic Ignition Switch (EZS) control unit |
| Electronic steering lock (ELV) control unit | ||
| 5 | 7.5 | Heater control unit (HAU) |
| Automatic climate control unit (KLA) | ||
| 6 | 15 | Horn |
| 7 | 25 | Fuel pump module (fuel pump fuse) with fuel level sensor |
| 8 | 25 | Overhead control panel (N70) |
| 9 | 40 | ESP and BAS control unit |
| 10 | 40 | Blower motor |
| 11 | 30 | Engine 266: Terminal 87 circuit relay, engine |
| 40 | Engine 640: Terminal 87 circuit relay, engine | |
| 12 | 5 | Steering column module (MRM) |
| Multifunction steering wheel | ||
| 13 | 25 | Front left door control unit |
| 14 | 25 | Front right door control unit |
| 15 | 25 | ESP and BAS control unit |
| 16 | 10 | Diagnostic link connector (OBD-II) |
| PARKTRONIC (PTS) control unit (2005–2008) | ||
| 17 | 5 | Exterior light rotary switch |
| 18 | 7.5 | Transmissions 711, 716: Backup light switch |
| 19 | 5 | Micromechanical yaw rate sensor (AY) |
| 20 | 7.5 | Supplemental Restraint System (SRS) control unit |
| 21 | 30 | Starter motor |
| 22 | 7.5 | Instrument cluster |
| 23 | 20 | Engine 640 (from Sep 1, 2008): Fuel filter water separator with heating element |
| 7.5 | 2005–2008: Heated windshield washer nozzles | |
| 24 | 7.5 | Electric Power Steering (EPS) control unit |
| 25 | 7.5 | Brake light switch |
| ESP and BAS control unit | ||
| 26 | 7.5 | Transmission 722: Electronic selector lever module (ESM) control unit |
| 27 | 10 | Transmission 722: CVT electrical control unit |
| 28 | 5 | Exterior light rotary switch |
| 29 | 30 | Signal Acquisition and Actuation Module (SAM) control unit |
| 30 | 25 | Terminal 87F circuit relay |
| 31 | 5 | Exterior light rotary switch |
| Central gateway / interface module (vehicles up to Nov 30, 2005) | ||
| 32 | 7.5 | Engine 266.920: ME engine control unit |
| 33 | 15 | Audio system |
| Audio and navigation unit | ||
| COMAND control unit | ||
| 34 | 25 | Rear left door control unit |
| 35 | 25 | Rear right door control unit |
| 36 | 10 | 2008–2012: PARKTRONIC (PTS) control unit |
| 7.5 | 2005–2008: Trailer module | |
| Mobile phone wiring connector | ||
| 37 | 7.5 | Supplemental Restraint System (SRS) control unit |
| Child seat recognition sensor (front passenger seat) | ||
| Front passenger seat occupancy sensor | ||
| 38 | 25 | Front cigarette lighter fuse (W245) |
| 39 | 25 | Windshield wiper motor |
| 40 | 25 | Louvered sliding roof: Overhead control panel (sunroof motor) |
| 7.5 | Overhead control panel | |
| 41 | 15 | Rear window wiper motor |
| 42 | 7.5 | Glove compartment light with microswitch |
| Left and right vanity mirror illumination | ||
| Dual pedal control sensor (driver training package) | ||
| Footwell light switch (driver training package) | ||
| VICS + ETC power supply connector (Japan) | ||
| Emergency call system module (TELE AID / USA) | ||
| 43 | 7.5 | Engine 266: Terminal 87M1e circuit connector |
| 15 | Engine 640: Terminal 87M1e circuit connector | |
| Bi-fuel gasoline engine: Terminal 87M1e circuit connector | ||
| 44 | 15 | Engine 266: Terminal 87M2e circuit connector |
| 20 | Engine 640: Terminal 87M2e circuit connector | |
| 45 | 25 | Engine 640: CDI control unit |
| 46 | 25 | Subwoofer (Japan, 2008–2012) |
| 40 | Audio amplifier (2008–2012) | |
| 7.5 | Universal Handy Interface (UHI) module (2005–2008) | |
| GSM 1800 compensator (2005–2008) | ||
| Telephone control unit (Japan, 2005–2008) | ||
| 47 | 7.5 | Mobile phone wiring connector |
| Universal Handy Interface (UHI) control unit | ||
| Voice control system control unit (2005–2008) | ||
| Telephone control unit (Japan, 2005–2008) | ||
| 48 | 7.5 | Anti-theft alarm (EDW) / tow-away protection / interior sensor control unit |
| Alarm siren | ||
| 49 | 25 | Front left seat cushion heater element (2005–2008) |
| Front left seat backrest heater element (2005–2008) | ||
| Front right seat cushion heater element (2005–2008) | ||
| Front right seat backrest heater element (2005–2008) | ||
| 50 | 7.5 | Media interface control unit (2008–2012) |
| Digital TV tuner (2008–2012) | ||
| DAB digital radio tuner (2008–2012) | ||
| CD changer (2005–2008) | ||
| VICS + ETC power supply connector (Japan, 2005–2008) | ||
| 30 | Special-purpose / service vehicles: Roof beacon | |
| Terminal 30 circuit wire connector | ||
| 51 | 10 | Weight Sensing System (WSS) control unit (Canada) |
| Special signals control panel (service vehicles) | ||
| 52 | 7.5 | Emergency call system control unit (vehicles up to May 31, 2006) |
| 5 | VICS + ETC power supply connector (Japan, vehicles up to May 31, 2006) | |
| 53 | 30 | Interior 12V power socket |
| Rear cigarette lighter fuse (W245) | ||
| 54 | 15 | Service vehicles: 2-pin 12V socket |
| 25 | Audio amplifier (2005–2008) | |
| Subwoofer (2005–2008) | ||
| 55 | 10 | Left headlight |
| 56 | 10 | Right headlight |
| 57 | 15 | 13-pin trailer hitch socket (2008–2012) |
| 20 | Audio interface (Japan, 2005–2008) | |
| 7.5 | Emergency call system | |
| Satellite radio tuner (SDAR) | ||
| 58 | 25 | Trailer recognition control unit |
| 59 | 20 | 13-pin trailer hitch socket |
| Trailer control unit (vehicles up to May 31, 2005) | ||
| 60 | 20 | Driver seat electrical contact strip |
| 61 | 20 | Front passenger seat electrical contact strip |
| 62 | 40 | 2008–2012: Terminal 15 (2) circuit relay (optional equipment: Xenon headlights, mobile phone) |
| 25 | 2005–2008: Terminal 15 (2) circuit relay (optional equipment: Xenon headlights, mobile phone) | |
| 63 | 7.5 | Satellite radio tuner (SDAR - Canada) |
| 25 | Roof beacon (service vehicles) | |
| 64 | 40 | Engine 266: Secondary air pump relay |
| 80 | Engine 640: Glow plug output stage | |
| 65 | 80 | Electric Power Steering (EPS) control unit |
| 66 | 60 | Signal Acquisition and Actuation Module (SAM) control unit |
| 67 | 50 | Terminal 15R (2) circuit relay (optional equipment) |
| 68 | 50 | Standard equipment (2008–2012): Engine and A/C electric suction fan with integrated controller (2005–2008: valid for engines 266.920 and 266.940 with transmission 722) |
| 60 | Special equipment (2008–2012) / 2005–2008: valid for engines 640.940, 640.941, 266.960, 266.980, and engines 266.920/266.940 with code 550 (Trailer hitch) | |
| 69 | 50 | Terminal 15R (1) circuits |
| 70 | 60 | Terminal 15 (1) circuits |
| 71 | 150 | Engine 640: PTC auxiliary heater |
| 72 | 60 | 2005–2008: Terminal 30 circuit wire connector |
| Service vehicles: Fuses 7 (F7f7) and 10 (F7f10) | ||
| Interior: Special-purpose vehicle control unit (MSS) | ||
Relay Box
The optional auxiliary relay panel (K100) is located under the dashboard on the passenger side.
To gain access:
1. Remove the trim panel beneath the glove compartment.
2. Remove the side trim panel near the door sill.
3. Fold back the floor carpet.
| Diagram | ||
|---|---|---|
|
||
| No. | Description | |
| A | Terminal 15R (2) circuit relay (optional equipment) | |
| B | Terminal 15R (1) circuit relay | |
| C | Horn relay | |
| D | Heated rear window relay | |
| E | Windshield wiper stage 1/stage 2 relay | |
| F | Windshield wiper ON/OFF relay | |
| G | Terminal 15 (1) circuit relay | |
| H | Reserved / Spare | |
| I | Engine 266: Secondary air pump relay | |
| K | Fuel pump relay (gasoline engines) | |
| L | Engine circuit terminal 87 relay | |
| M | Starter motor relay | |
| N | Terminal 87F circuit relay | |
| O | Terminal 15 (2) circuit relay (optional equipment: Xenon headlights, mobile phone) | |
| No. | Description | A |
| 80– 81 |
Special equipment / Options | 30 |
Electrical Component Locations
General overview of electrical component locations in the vehicle:
1. ABS/ESP control unit;
2. Blower motor resistor;
3. Climate control module – behind the climate control panel;
4. A/C humidity sensor – on the air intake duct;
5, 6. Roof antenna;
7. Side impact sensor, driver side;
8. Side impact sensor, passenger side;
9. Anti-theft alarm control unit;
10. Anti-theft alarm siren – on the air intake duct;
11. Solar sensor;
12. Audio amplifier – behind the right rear quarter trim panel;
13. Auxiliary heater control unit – integrated into climate control panel;
14. Battery – front passenger footwell;
15. CAN bus gateway control unit (audio system) – behind the right rear quarter trim panel;
16. Central gateway module (CGW) – behind the dashboard;
17. Compass module – behind the instrument cluster;
18. Diagnostic link connector (DLC / OBD-II);
19. Driver door control unit – inside the door;
20. Left rear door control unit – inside the door;
21. Right rear door control unit – inside the door;
22. Front passenger door control unit – inside the door;
23. Diesel engine control unit (CDI ECU);
24. Gasoline engine control unit (ME ECU);
25. Auxiliary relay panel – beneath dashboard;
26. Main fuse box – front passenger footwell;
27. Left Xenon headlight control unit – under left headlight assembly;
28. Right Xenon headlight control unit – under right headlight assembly;
29. Left headlight range adjustment motor;
30. Right headlight range adjustment motor;
31. Horn;
32. Electronic Ignition Switch (EZS);
33. Immobilizer control unit – integrated into Electronic Ignition Switch (EZS);
34. Immobilizer antenna ring – integrated into Electronic Ignition Switch (EZS);
35. Natural gas / CNG system control unit;
36. Signal Acquisition and Actuation Module (SAM) – controls central locking, exterior/interior lighting, hazard/turn signals, windshield/rear wipers and washers, horn, rear window defroster, coolant/brake fluid level sensors, backup light switch, and tailgate release;
37. Media interface control unit;
38. Multifunction steering wheel control unit;
39. Navigation control unit – integrated into audio head unit;
40. Outside air temperature sensor – behind front bumper;
41. PARKTRONIC (PTS) control unit – behind right rear quarter trim panel;
42. Electric power steering (EPS) control unit – mounted on steering rack;
43. Rain/light sensor – top center of windshield;
44. Steering column module (MRM) – behind steering wheel;
45. Electronic steering lock (ELV) control unit – on steering column;
46. Subwoofer – behind left rear quarter trim panel;
47. Airbag / SRS control unit – under center console;
48. Universal phone interface (UHI) control unit – under front passenger seat;
49. Trailer recognition module – behind right rear quarter trim panel;
50. Automatic transmission control unit (TCM) – integrated into transmission;
51. Electronic selector lever module (ESM) – integrated into gearshift lever.
Very helpful