Mercedes w203: fuses and relays

The Mercedes 203 C-Class is the second generation of the model range, which was produced in 2000, 2001, 2002, 2003, 2004, 2005, 2006 and 2007 with w203 sedan, s203 station wagon, coupe (C160, C180, C230, C240), C280, C320). During this time, the model has been redesigned. In this publication you will find information on the location of electronic control units, a detailed description of the fuses and relays Mercedes 203 with block diagrams and photo examples of their location. Pay attention to the fuses responsible for the cigarette lighter and fuel pump.

The location of the blocks and the location of the elements on them may differ from those shown and depend on the year of manufacture, the region of delivery and the level of electrical equipment of your car.

Location

General arrangement of electronic control units

Description

one	Air conditioning / heating control unit - in the heating control panel
two	A/C/Heater Fan Control Module - Near the fan motor
3	Air purity sensor (air conditioning system)
4	Sunlight sensor (air conditioning system)
5	Antenna signal amplifier - 1, at the top of the rear window
7	Anti-theft control unit (built into the multifunction control unit) - left side of the trunk
eight	Vehicle inclination sensor (anti-theft system) - left side of trunk
nine	Anti-theft horn - behind wheel arch trim
ten	Volume change sensors (anti-theft system)
11	Audio block - in the navigation system
12	Audio Output Amplifier (If Equipped) - Right Trunk Side
thirteen	Additional heating control unit
14	Auxiliary Heater Remote Control Receiver - Under Dashboard (Rear Luggage Compartment)
fifteen	Accumulator battery
sixteen	Brake booster vacuum pump control unit
17	Central locking signal sensor (infrared) - on the driver's door handle
Eighteen	Diagnostic connector (DLC)
nineteen	Electric control box driver's door
twenty	Rear left door electric control box
21	Passenger door electric control unit
22	Rear right door electronics control unit
23	Fuse / relay box, engine compartment 1
24	Fuse/Relay Box
25	Fuse/Relay Box, Trunk
26	Left headlight control unit (models with xenon headlights)
27	Right headlight control unit (models with xenon headlights)
28	Sound signals 1/2 - behind bars
29	Ignition lock control unit
30	Electronic immobilizer control unit (integrated with ignition lock control unit)
31	Turn Signal/Hazard Relay - In Multifunction Control Module 2
32	Lighting control unit - behind the headlight switch
3. 4	Multifunction Control Module 1 - Connected to Engine Compartment Fuse/Relay Box - Functions: Interior Lights, Headlights, Horn, Wipers, A/C Pressure Control, Headlight Washers, Coolant Level, Brake Fluid Level, Thermometer, Power Outside Mirrors
35	Multifunction control unit 2 - connected by fuse / relay box, trunk - functions: central locking, fuel level, anti-theft system, alarm, heated rear window, taillights, trunk lid opener, rear wiper (wagon)
36	Navigation system control unit
37	Room temperature sensor
38	Parking system control unit - under the panel, in the rear of the trunk
39	Rain sensor - top center of windshield
40	Power seat control unit (with memory), front left - under the seat
41	Power seat control unit (with memory), front right - under the seat
42	Front seat heating control unit - in the switch box
43	Electronic transmission - sequential manual transmission
44	Side impact sensor on the left under the rear seat
Four five	Side impact sensor, right - under the rear seat
46	SRS electronic control unit
47	Steering column electric control unit - behind the steering wheel
48	Steering column lock control unit - built into the ignition lock control unit
49	Electric sunroof control
50	Body height sensor, front (models with xenon headlights) - front anti-roll bar
51	Body height sensor, rear (models with xenon headlights) - rear axle
52	Telephone network connection module - under the panel, in the rear of the trunk
53	Telephone interface control unit - under the panel, in the rear of the trunk
54	Handset - under the panel, in the rear of the trunk
55	Electric trailer control unit - under the panel, in the rear of the trunk
56	Electronic transmission control unit
57	Shift Control Module - Automatic Transmission Selector
59	Voice control unit - under the panel, in the rear of the trunk
60	Fuse / relay box, engine compartment 2

Location of fuse and relay boxes in Mercedes 203

designation

• F32 - power fuse box
• F34 - Fuse box in the dashboard
• N10 / 1 - Fuse box and relay in the engine compartment
• N10 / 2 - Fuse box and trunk relay

Block in the cabin

In the cab, the fuse box is located on the left side of the dashboard under a protective cover.

scheme

Goal

21	30A Left front door control unit
22	30A Right front door control unit
23	15A cigarette lighter
24	7,5A CD player with changer (in glove box)
25	30A Upper control panel control unit
26	25A audio amplifier
27	30A Power driver's seat control unit (with memory)
28	Spare fuse 30A
29	30A Power driver's seat control unit (with memory)
Multifunctional control unit (taxi)
30	Heater air circulation unit 40A
31	EIS 20A control unit
Ignition lock control unit
32	30A Left rear door control unit
33	30A Right rear door control unit
3. 4	7,5A terminal 30 socket
Before 31.05.01:
Mobile phone and D2B transceiver (for built-in phone)
Cell phone and TELE AID D2B transceiver (for built-in phone)
Phone interface (for optional cell phone)
Compensator CTEL (for additional cell)
15A Before 31.3.04: Power passenger seat control unit (with memory)
Until 31.05.03/XNUMX/XNUMX, Taxi: Multifunction switch
From 1.6.03, Taxi: Multifunction Switch
As of 1.6.01, Police: Multifunctional control unit
30A From 1.4.04: Power passenger seat control unit (with memory)
From 1.4.04, Taxi: Multifunction control unit
35	30A Up to 31.03.04: STH heater
20A From 1.4.04: STH heater
36	30A Before 31.3.04, Police: additional power socket
Engines 15A 612.990 (up to 29.2.04): charge air cooler circulation pump
From 1.4.04, Japan: Audio Interface Control Unit
7,5A universal mobile phone interface
37	25A air cooler circulation pump
Up to 29.2.04: Brake booster vacuum pump control unit
38	30A Before 29.2.04: Power passenger seat control unit (with memory)
From 1.4.04, Police: Multifunction control unit
39	Spare fuse 30A
40	7,5A Power passenger seat control unit (with memory)
Universal mobile phone interface
cell phone split point
Telephone interface
Radiotelephone network compensator E
From 1.6.01, MB phone: cell phone and transceiver
As of 1.6.01 TELE AID: cellular communication and transceiver
From 1.4.04, Japan: ECU
30A Up to 31.5.01: Multifunction control unit
41	7.5A Upper control panel control unit
Until 31.05.01/XNUMX/XNUMX: KLA control panel (automatic climate control)
15A From 1.6.01: KLA system control panel (Automatic climate control system)
42	7.5A Instrument cluster

In the Mercedes 203, fuse 23 is responsible for the cigarette lighter. Another fuse is located in the block under the hood or in the trunk (USA).

Block under the hood

Main unit

Under the hood in the engine compartment on the left side under the protective cover is the fuse and relay box.

scheme

transcribed

43a	15A Horn relay
43б	15A Horn relay
44	5A D2B-interface
Telephone interface
Ferrule connector 15R
TELE AID switchboard
Four five	SRS control unit 7.5A
46	40A Wiper On/Off Relay
Wiper Mode Relay 1/2
47	15A Glove box lighting with sensor switch
Front cigarette lighter (illuminated)
48	15A Engines 612.990 (up to 31.3.04): Brake booster vacuum pump control unit
Motors 112, 113: Coupling sleeve protected by fuse 15
Engines 646, USA (until 31.03.04/30/XNUMX): Coupling with fuse XNUMX
646 engines (since 1.4.04): O2 sensor before catalytic converter
49	SRS control unit 7.5A
50	Light switch module 5A
Engines 612 990
The final stage of the warm-up (until 31.03.04)
Mass air flow sensor (from 1.4.04 to 30.11.04)
51	7,5A AAC (automatic air conditioning) with built-in auxiliary fan motor
Tool combination
For AAS "comfort":
AAC malfunction sensor
Solar radiation sensor AAC (4 pcs)
For all vehicles with xenon headlights:
Left block headlight
Right block headlight
AMG: air cooler circulation pump
203.0 (until 31.7.01): SRS control unit
52	15A starter
53	Diesel engines 25A:
Starter relay
Rear SAM control unit with relay and fuse box
Engines 611/612/642/646: CDI control unit
Gasoline engines 15A:
Starter relay
Rear SAM control unit with relay and fuse box
Engines 111/271/272: ME control unit
Engines 112/113:
ME control unit
Electrical cable connection terminal 87 M1e
54	Engines 15A 271.940:
ME control unit
Vent valve (USA)
Container stop valve
Engines 271.942: NOX control unit
Engines 642/646: CDI control unit
Engines 642/646: Termination of electrical cable terminals 30 circuits
Engines 7,5A 611/612: CDI control unit
Engines 611/612 (up to 30.11.04/XNUMX/XNUMX): Resistance in the ventilation duct
55	Flywheel sensor 7,5A
Distronic: DTR control unit
722 gearbox:
ETC control unit [EGS] (up to 31.5.04)
Selector lever electronic control unit
VGS control unit
716 gearbox:
sequencetronic control unit
Transmission Position Sensor
56	5A ESP and BAS control unit
Brake light switch
57	5A Steering wheel sensor (up to 31.5.02)
Electronic ignition control unit / sensor-switch that opens the starting circuit
Steering column electronic module (as of 1.6.02)
Engines 112/113: ME control unit
58	40A Transmission 716: Hydraulic pump
59	50A ESP and BAS control unit
60	40A ESP and BAS control unit
61	15A Transmission 716: Sequentronic control unit
62	Diagnostic connector 5A
Lighting control module
Brake light switch
63	5A lighting control module
64	10A radio receiver
Radio and navigation
Display and control unit for COMAND functions
sixty five	40A 112/113 Motors: Electric air pump
Relay
Я	Horn relay
К	Terminal 87 relay, chassis
Л	Wiper Mode Relay 1/2
METER	Relay terminal 15R
North	Pump control relay KSG
OR	Air Pump Relay (Engines 112, 113, 271)
П	Relay terminal 15
Question	Wiper On/Off Relay
Р	Terminal 87 relay, motor
Yes	Starter relay

Power unit

An additional high power fuse block in the form of fuse holders is installed next to the battery.

Photo example

scheme

Description

1. 125A fuse box in the instrument panel
2. Control unit SAM 200A, rear
3. 125A Additional fuse box
4. 200A SAM control unit, front
5. 125A Electric suction fan for engine and air conditioner with built-in regulator
   
   Diesel engines: the final stage of preheating
6. 60A SAM control unit, front

block in trunk

It is located in the trunk, behind the upholstery.

scheme

designation

one	30A Right front seat adjustment switch block
Switch for partially electric adjustment of the front passenger seat
two	30A Left front seat adjustment switch block
Power driver's seat partial adjustment switch
3	7,5 A Interior lighting
Trunk lighting
remote control receiver
Tire pressure monitoring
20A TV tuner
4	Fuel pump relay 20A
5	20A Engines 112.961 (up to 31.3.04): charge air cooler circulation pump
Except 112.961: Spare relay 2
6	Spare fuse 25A
7	7,5 A Backup relay 1
eight	Rear window antenna booster module 7,5 A
alarm siren
ATA tilt sensor
nine	25A Upper control panel control unit
ten	40A Heated rear window
11	Spare fuse 20A
12	Auxiliary power connector 15 A
203.0 - USA (until 31.03.04/XNUMX/XNUMX): Rose window
thirteen	5A Air pump for multi-contour seat
Voice Control System (VCS) - Voice Control Unit
Motorola Star TAC Cell Phone Upgrade - Portable Cell Phone D2B Interface
Rear Reading Light
Indication of the PTS signal (parktronic)
PTS control unit (parktronic)
14	15A Rear wiper
fifteen	10A Fill relay, receiver polarity
sixteen	20A For VSC: Voice control unit
Update for Motorola Star TAC CTEL: D2B interface for mobile phone
17	20A Trailer control unit
Eighteen	Drawbar socket 20A, 13 pins
nineteen	20A Air pump for multicontour seat
twenty	15A Dimming rear window
203.2/7 - USA: Rose Window
Relay
AN	Fuel pump relay
Б	Relay 2, terminal 15R
С	Backup relay 2
Д	Backup relay 1
Me	Rear heater relay
Ф	Relay 1, terminal 15R
GRAM	Fill relay, polarity switch 1
TIME	Fill relay, polarity switch 2

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