Mercedes ML W166 represents the third generation of M-class SUVs Mercedes-Benz which was produced in 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 and was supplied all over the world. During this time, the model was restyled. This information will also be useful for owners of Mercedes GL X166 and Mercedes GLS X166 , since these cars have similar electrical circuits. In it you can find a description of the fuses and relays Mercedes 166 with block diagrams, photo examples of their execution and locations. Note the fuse responsible for the cigarette lighter.

The purpose of the fuses and relays in the blocks may differ from that shown and depends on the year of manufacture, equipment level and region of delivery of your vehicle.

Blocks under the hood

Location

Scheme

Description

  • F32/3 – Power fuse box
  • F58 – Fuse and Relay Box

Fuse and relay box

Photo – example

Designation

201Reserve
20220A Heating device of independent heater
2035A Alarm Siren
20425A Electronic stability control unit
20515A Left horn
Right horn
206Reserve
207Reserve
208Reserve
209Reserve
210Reserve
211Reserve
212Reserve
2137.5A Valid for motors 642, 651:
CDI control unit
Valid for engine 157, 276, 278:
ME control unit
21415A Valid for engine 157, 276, 278:
ME control unit
Valid for vehicles with 651 engine:
CDI control unit
BlueTEC:
Nox sensor control unit
21515A Valid for vehicles with engine 157, 276, 278:
Electrical plug connection engine/engine compartment (terminal 7)
Valid for vehicles with engine 642:
Electrical plug connection engine/engine compartment (terminal 7) via cable end sleeve terminal 87 D3
Radiator shutter actuator
Valid for vehicles with 651 engine:
Electrical plug connection engine/engine compartment (terminal 7)
Radiator shutter actuator
21615A Valid for engine 157, 276, 278:
Cable termination joint, terminal 87D2
Valid for vehicles with engine 642:
CDI control unit
Electrical plug connection engine/engine compartment (terminal 6)
Adjustable left engine mount
Adjustable right engine mount
Valid for vehicles with 651 engine:
Fan motor
CDI control unit
Electrical plug connection engine/engine compartment (terminal 6)
Adjustable left engine mount (Y123) Adjustable right engine mount
21720A Valid for engine 157, 276, 278:
Electrical plug connection engine/engine compartment (terminal 5)
Valid for engines 642, 651:
CDI control unit
Electrical plug connection engine/engine compartment (terminal 5)
218Reserve
21910A Valid for engine 278, 157: Charge air cooler circulation pump
220Reserve
222Reserve
223Reserve
224Reserve
225Reserve
226Reserve
227Reserve
228Reserve
2297.5A Front Left Headlight
2305A Electronic stability control unit
2317.5A Front Right Headlight
23215A Control unit for fully integrated gearbox control system
Vehicles without “ECO Start-Stop” function: Control unit for additional transmission oil pump
23315A Headlight Control Unit
2345A Electrical control module DISTRONIC
23520A Windscreen wiper heating
236Reserve
23715A KP 722.9: Automatic transmission servo drive module for DIRECT SELECT system
23840A AIRMATIC Compressor
23930A Windscreen Wiper Motor
240a30A Vehicles without “ECO Start-Stop” function: Starter
240b30A Vehicles with “ECO Start-Stop” function: Engine compartment power fuse box
241Reserve
Relay
JSound signal relay
KWindscreen wiper mode relay 1/2
LWindscreen wiper relay on/off
MStarter terminal 50 relay
NRelay electric circuit terminals 87M
THETurbocharger relay
PReserve relay
QRelay terminal 15 (without support)
RRelay terminal 15
SWindscreen wiper heating relay
TAIRMATIC relay

Power fuse box

Photo

Transcript

25040A SAM Control Unit
25140A SAM Control Unit
25240A SAM Control Unit
25330A Front Left Door Control Unit
25430A Rear Left Door Control Unit
255200A Battery Compartment Power Fuse Block
256150A Rear Passenger Compartment Fuse Box
257150A Diesel Engine: Additional Electric Heater

It is possible to install some relay elements outside of these blocks, for example, a relay for heating the hoses to the washer nozzles.

Blocks in the cabin

Location

Scheme

Purpose

  • F3/2, F3/3 – Fuse box in the instrument panel
  • F4 – Main fuse and relay box in the rear of the passenger compartment
  • F32/4 – Power fuse box
  • F33 – Battery compartment fuse box
  • F270 – Buffer battery fuse

Fuse and relay box

The main block with fuses and relays in the passenger compartment is located under the rear seat and is covered with a protective cover.

Description

1005A Audio module
COMAND control module
External navigation electrical plug connection
10120A Trailer Recognition Control Unit
1027.5A Driver Seat Control Unit
1037.5A Front Passenger Seat Control Unit
1045A Mobile Antenna Amplifier/Compensator
Bluetooth® Module
1055A Holder for navigation module
1065A Tailgate Drive Control Unit
10710A 2nd Row Left Seat Release Module
2nd row seat release module right
108Reserve
109Reserve
1105A AdBlue® Control Unit
11115A Trailer Socket
1125A Fuel Pump Control Unit
1135A Electric Parking Brake Control Unit
1145A Outdoor Lighting Switch
1155A Trailer Recognition Control Unit
1165A Radar Sensor Control Unit Terminal 87 Termination Sleeve
COLLISION PREVENTION ASSIST control module
1175A Night Vision Control Unit
118Reserve
1195A Transfer Case Control Unit
1205A Fuel quality sensor
Digital tachograph control unit
121Reserve
122Reserve
123Reserve
12430A Electrical plug connection for Elektric Brake Control function
125Reserve
12615A Trailer Recognition Control Unit
12730A Driver Seat Control Unit
12820A Trailer Recognition Control Unit
12930A Front Passenger Seat Control Module
13020A Trailer Recognition Control Unit
131Reserve
13225A Fuel Pump Control Unit
1335A Receiver for remote control of independent heater
1345A Seat occupied recognition system pressure sensor
Front passenger seat occupancy recognition system and AKSE
1355A Glove box light
1367.5A Supplemental Restraint System Control Unit
1375A Electrical Fuse Preparatory for Installation of Electronic Toll Collection System
Electronic equipment rear view camera
External navigation electrical plug connection
13815A Active Roll Stabilization Control Unit
139Reserve
1407.5A AdBlue® Control Unit
14115A AdBlue® Control Unit
14220A AdBlue® Control Unit
143Reserve
144Reserve
1457.5A Cup Holder
14630A Rear Window Rejector Filter
14730A Audio module
COMAND control module
14815A Cigarette Lighter Heating Element
Detachable cup holder connection
1495A 115V Socket
15020A Socket in the trunk
15120A Socket 2nd row seats left
Power outlet in the 2nd row of seats on the right
15230A Rear compartment systems control unit
15325A AC/DC Converter Control Unit
15440A Tailgate Drive Control Unit
155Reserve
156Reserve
15715A Tailgate Windscreen Wiper Motor
Relay
ARelay socket terminals 15R2
BRear window heating relay
CBackup relay
DAdBlue ® relay
ANDRelay terminal 15
FRear Window Wiper Relay
GRelay terminals 15R1
HBackup relay
IBackup relay

Fuses 148–151 are responsible for the cigarette lighter.

Fuse box in the panel

At the right end of the instrument panel, behind the protective cover, there is a fuse box.

Designation

107.5AElectronic ignition switch control unit
1110AElectronic Steering Column Module Control Unit
125AInstrument cluster
1315AElectronic auxiliary fan controller
145ADiagnostic connector
155AUpper control panel
16Reserve
17Reserve
18Reserve
1915AClimate control system control panel
205AElectronic Steering Column Module Control Unit
217.5ADisplay Audio/COMAND
22Reserve

Fuse box near the battery

Another block of fuses is installed in the niche next to the battery.

Purpose

3040A Speaker Amplifier Control Unit
30A Woofer Amplifier
3140A Engine Compartment Fuse and Relay Module
3240A Fan Controller
3340A Front Left Reversible Seat Belt Tensioner
3440A Rear Fuse Box
3540A Front Right Reversible Seat Belt Tensioner
3640A Fuse Box Terminal 30 Front Panel
3740A Test Lead
38Reserve
39Reserve
4025A Electronic control of the rear air conditioning fan
41Reserve
42Reserve
43Reserve
44Reserve
455A Digital tachograph control unit
46Reserve
4710A Speaker Amplifier Control Unit
4830A Rear compartment systems control unit
495A EDW/Towaway/Interior Security Control Unit
505A Emergency Call System Control Unit
515A Antenna amplifier FM 1, AM, ZV and KEYLESS-GO
5230A Front Right Door Control Unit
5315A Ceiling Control Panel
54Measuring wire
5530A Rear compartment systems control unit
5615A Keyless-Go Control Unit
5730A Rear Right Door Control Unit
5830A Transfer Case Control Unit
597.5A Supplemental Restraint System Control Unit
607.5A Ceiling Control Panel
61Reserve
6215A AIRMATIC control unit
6320A Panoramic Sliding Sunroof Control Module
Sliding Sunroof Control Module
6430A Multi-contour seat air pump
6530A Fuse Box, Terminal 30g, Front Panel
66Reserve
6730A Electric Parking Brake Control Unit
6830A Electric Parking Brake Control Unit
MF15A Pin 1: Audio module/COMAND system control panel
Contact 2:
Lower control panel
Off-road driving mode control panel
Contact 3: Parking assistance control unit
Contact 4: Electronic stability control unit
Contact 5: SAM Control Unit
Contact 6: Speaker Amplifier Control Unit
MF25A Contact 1: HBF Control Unit
Contact 2: Tire pressure monitoring system control unit
Contact 3:
Digital Sound Broadcasting Control Unit
Satellite Digital Audio Radio (SDAR) Control Unit
Contact 4: Multifunctional camera
Contact 5: Multimedia Interface Control Unit
Contact 6:
Rear view camera
360° Camera Control Unit
MF35A Contact 1: Rear left display
Contact 2: Display in the rear compartment on the right
Contact 3:
TV tuner (analog/digital)
Digital TV tuner
Contact 4: DVD Player
Contact 5: Video and radar sensor control unit
Contact 6: Reserve
MF4Contact 1: Reserve
Contact 2: Reserve
Contact 3: Reserve
Contact 4: Reserve
Contact 5: Reserve
Contact 6: Reserve

Power fuse box

This high power fuse block is also located near the battery.

Transcript

140AElectronic stability control unit
2Reserve
330AVehicles with “ECO Start-Stop” function: Engine compartment fuse and relay module
4Reserve
5150AEngine Compartment Fuse and Relay Module
6125AFan motor
7300/400APassenger compartment fuse box
8100AElectric Power Steering Control Unit