Mercedes W168 represents the first generation of the A-class of the Mercedes-Benz model range, which was designated A140, A150, A160, A170, A180, A190, A200 and A210 and was produced in 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004. During this time, the model was restyled. In this publication, you will find information about the location of all electronic control units, a description of fuses and relays Mercedes w168 with block diagrams and photo examples of their implementation. Let’s highlight the cigarette lighter fuse.

The purpose of the fuses and relays may differ from that shown and depends on the year of manufacture and the level of equipment of your car.

Location

General layout of all electronic control units

Purpose

1Air conditioning control unit – in the heater control panel
2Antenna signal booster
3Anti-theft alarm control unit – interior lighting lamps
4Vehicle tilt sensor (anti-theft system) – in the anti-theft system control unit
5Anti-theft alarm sound signal
6Volume change sensors (anti-theft system) – in the anti-theft system control unit
7Anti-theft alarm control unit – in the immobilizer control unit
9Remote control receiver for additional heater
10Battery – Passenger Side Footwell
12Clutch actuator control unit
13Diagnostic Link Connector (DLC)
14Electric window lift control unit – in the front window lift control panel
15Left front window lift control unit – in the window lift drive motor
16Left rear window lift control unit – in the window lift drive motor
17Right front window lift control unit – in the window lift drive motor
18Right rear window lift control unit – in the window lift drive motor
19Fuse/Relay Box Instrument Panel
20Fuse/Relay Box, Footwell
21Fuse/Relay Box, Engine Compartment
22Sound signals – behind the front bumper
23Electronic immobilizer control unit
24Ring antenna of the immobilizer – near the ignition switch
26Lighting control unit – in the headlight switch
27Multifunctional control unit – functions: Central locking, direction indicators, sunroof – in the instrument cluster
28Navigation system control unit – in the audio system unit
29Ambient air temperature sensor
30Parking system control unit
31Rain sensor – in the interior rearview mirror
32Seat heating control unit – in switch block
33Side impact sensor, left
34Side impact sensor, right
35SRS Electronic Control Unit
36Telephone Network Connection Module
37Phone Interface Control Unit
39Windshield Wiper Intermittent Relay – Windshield Wiper Motor

Blocks in the cabin

Main block

The main fuse and relay box is located next to the battery, on the front passenger side, under a cover in the footwell. To remove the cover, turn the fastening clips.

Description

120A Petrol engines:
Fuel Tank Ventilation Valve Fan Relay
Fuel injection control unit
Idle speed control unit
EGR valve
Lambda probe heater 1
Lambda probe heater 2
Diagnostic connector
Cruise control
Relay boost
Boost Valve (US Models)
Fuel Shut-Off Valve (US Models)
10A Diesel Engines:
Fan relay
Diesel Engine Power Control Unit
Diaphragm valve
Throttle valve
EGR valve
Catalyst temperature sensor
225A Engine Control Unit
Ignition coils
Fuel injectors
Fuel pump relay
Electronic accelerator
Starter lock and cut-off relay
330A Vehicles without air conditioning: Engine cooling fan
40A Vehicles with air conditioning: Engine cooling fan
47.5A Engine Control Unit
540A Automatic Clutch
630A Fuel Pump Relay
740A Car Light Unit
830A Starter Lock and Cut-off Relay
940A Wiper Motor
1020/40A Hatch
Rear window cleaner
1115A Cigarette Lighter
Steering column switch:
Glass cleaner
Sound signal
Washer pump
Radio navigation system
1230A Socket in the trunk of the radio
Radio
Glove box light
CD changer
1330A Front door windows
7.5A Power windows for all doors
1410A Instrument cluster (clock)
Windscreen wiper and washer relay
Mobile phone
1510A Airbag Unit
Child seat recognition unit
Side airbag sensor
1615A Drive for exterior mirrors and mirror heater
Parking assistance system
1715A Sound signal
1810A Instrument cluster
Transmitter and receiver of signal from remote control
Electronic Engine Control Unit Relay
Fan relay
1930A Towing hitch
2015A Towing hitch
2115A Towing hitch
2225A Audio system
237.5A Mirror Light
24Not used
25Not used
26Not used
27Not used
2810A Instrument cluster
Window lifters
2915A Central locking
Seat position recognition unit
307.5A Transponder and receiver of signal from remote control
Electronic instrument panel
3125A Rear Window Defogger
3215A Mobile phone
Radio receiver or radio navigation system
CD changer
Interior lighting
3330A Window Lifters
3430A Fuel Filter Heater
40A Supercharger (US models)
3510A Security Alarm Control Unit
2x relays for light and sound signaling
3625A Heated front seats
3710A Program Switch
Coolant Heater Relay
3810A Air Conditioning Compressor
Electric motor of air mixing damper
Cabin air temperature sensor
Washer Jet Heater
397.5A Lighting Module
Reversing light
4010A Brake lights
4110A Air Conditioning Compressor
Diagnostic connector
42Window lifters
4315A ESP
Brake Light Switch Sensor
4410A Gearbox or Automatic Clutch Control Unit
4530A Interior Heater Fan
Air conditioner fan
4680A On-board network fuse
4760A Power Steering Pump
4860A Diesel Engines: Preheat Control Unit
Relay
K7Fuel pump relay (002 542 13 19)
K8Fuel and ignition control unit relay (002 542 25 19)
K9ESP/VGS or ESP/automatic transmission relay. VGS gearbox control unit (002 542 25 19)
K10Rear Window Defogger Relay (002 542 13 19)

Fuses number 11 and 12 are responsible for the operation of the cigarette lighters.

Additional block

Another fuse box is located on the back of the instrument panel, also covered with a protective cover.

Scheme

Designation

  1. 7.5A – Left low beam headlight
  2. 7.5A – Right low beam headlight
  3. 15A – High beam, High beam indicator
  4. 7.5A – Left parking light, Left rear side light
  5. 15A – Right parking light, Right rear side light, Number plate light, Instrument cluster, terminal 58
  6. 15A – Fog lights, Rear fog light left

Block under the hood

Under the hood, on the right side of the engine compartment, a block with a relay is installed.

Transcript

K1Washer pump relay
K2.0horn relay
K2.1Electronic Stability Program (ESP) relay
K3starter lock and cut-off relay
K4radiator fan relay
K5ESP pump relay
K6Air Pump Relay (US Models)