No.
Relay assignment
J
Terminal 15
K
Terminal 15R
L
Spare
M
Terminal 50, starter
N
Terminal 87 motor
O
Horn
P
Catalyst purge
Q
oil cooler fan
R
Terminal 87 running gear
No.
A
Purpose of fuses
1
25
electronic stability control system ESP
2
30
front left door
3
30
Front door module on the right (up to 31.3.10)
4
7.5
Fuel pump fuse (gasoline engines)
Left fuel pump module (motor 156)
Right fuel pump module (motor 156)
Condensation sensor in the fuel filter with a heating element (engines 642, 651)
The control unit for the condensate sensor in the fuel filter with a heating element (motors 651 (up to 31.5.10), 646)
20
Headlight module (since 1.3.11)
5
7.5
Rear SAM unit with fuse and relay module
Relay for the coolant circulation circuit of the rear axle gearbox (engine 156 with 1.7.11)
Outdoor lighting switch (from 1.12.09)
6
10
CDI Block (Diesel Engines)
ME block (petrol engines)
7
20
Starter
8
7.5
Passenger restraint system module
9
15
Socket in the glove compartment
10
30
Wiper motor
11
7.5
Audio display / COMAND
Audio control panel / COMAND
Holder for navigation module
12
7.5
Climate control system control unit
Upper control panel
13
7.5
Steering column electronics control unit
Multifunctional camera (since 1.3.11)
14
7.5
Control unit for electronic stability control ESP
15
7.5
restraint system
passive safety systems
16
5
Diagnostic connector (up to 31.5.09)
Electr. mobile phone plug connection (up to 2008)
electronic module of the selector lever (KP 722)
17
30
Panoramic sliding sunroof control module
overhead control panel
18
7.5
Outdoor lighting parting switch (up to 2008)
upper control panel (from 1.3.11)
Termination of the positive cable of the LIN data bus of the air conditioning system of the instrument panel (up to 28.2.
Electrical connector for passenger compartment and wiring harness for tail lamp
19
20
Electric steering lock unit
Electronic ignition lock unit
20
40
ESP motion stabilization system
21
7.5
Brake signal sensor
Glove compartment light switch
Seat occupied recognition, front passenger seat occupied AKSE
Electric fuse for preparation for installation of the Electronic Toll Collection system (Japan)
22
15
Internal combustion engine blower motor and air conditioner with integrated regulation
Electrical connector for interior wiring harness and engine wiring
Cable lug electr. terminal 87 circuit M2e (engine 271; South Korea), (engine 272; USA)
ME control unit (engine 271; South Korea)
Regeneration changeover valve (engine 271; South Korea), (engine 272; USA)
CDI system control unit (engines 642, 646)
Heating element in the ventilation duct of the engine crankcase (engine 642)
Cable lug electr. terminal 87 circuits (engine 646)
23
20
Electrical connector for interior wiring harness and engine wiring
Rear SAM control unit with fuse and relay module (diesel engines)
CDI control unit (diesel engines up to 2008)
Cable lug electr. terminal 87 circuits (diesel engines up to 2008)
Cable lug electr. circuit terminal 87 M1e (motor 271 up to 2008)
Cable lug electr. circuit terminal 87 M1i (motor 272 up to 2008)
24
15
Electrical connector for interior wiring harness and engine wiring
Radiator shutter actuator (motor 642)
CDI control unit (motor 646)
Cable lug electr. circuit terminal 87 M1i (motor 272 up to 2008)
Cable lug electr. terminal 87 circuits (diesel engines up to 2008)
25
15
ME control unit (engines 156, 271, 272, 274, 276)
Lambda probe in front of the catalytic converter (engine 651)
Exhaust gas generator control unit (engine 651)
26
20
Audio module
Audio module with Auto-Pilot system
COMAND module
27
7.5
Electronic ignition lock unit
electric steering lock (up to 2008)
BCDI (diesel engines)
ME (gasoline engines)
28
7.5
Instrument cluster
29
10
Front right headlamp
30
10
Front left headlamp
Electrical connector for wiring harness, passenger compartment and engine (engine 642)
31A
15
Left horn
Right horn
31B
15
Left horn
Right horn
32
40
Electric air pump (engines 156, 271, 272)
33
10
Electronic control unit for automatic transmission control (KP 722.6)
Fully integrated automatic gearbox control unit (KP 722.9)
34
7.5
Fuel pump control unit (motors 274, 276), (motors 271, 272, 651 from 1.6.09), (motor 642 from 01.12.09)
35
5
ESP motion stabilization system (since 2009)
36
7.5
DISTRONIC electrical module
Electro-hydraulic power steering (since 2009)
Splendid diagram, saved an awful lot of time digging out wiring circuit data. Thanks for posting this vital must have info.