MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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In this guide (5 sections)
Here is the list of fuse designations for the Mercedes-Benz C-Class. It is a combined list of all the fuses, including pre-facelift and facelift models through 2007. The fuse box locations come first, with pictures, and the full chart follows. This guide covers W203 C-Class models from 2001 through 2007. Fuse assignments can vary by model year, engine, body style, market, and installed equipment. Check the fuse allocation chart supplied with your vehicle before replacing a fuse.
Where the Fuse Boxes Are on a W203
- Fuses 21 through 42 are located on the driver’s side of the dashboard.
- Fuses 1 through 20 are located in the trunk.
- Fuses 43 through 63 are located under the hood, near the hood hinge on the driver’s side.
Take a look at the pictures for the exact location.
This is the one thing worth memorizing before you use the chart below, because the chart gives numbers and nothing else. On a W203 the numbering is split cleanly by location.
| Fuse numbers | Where to go | What tends to live there |
|---|---|---|
| 1 to 20 | Trunk, behind the trim | Rear circuits, trunk lid, amplifier, rear power outlet |
| 21 to 42 | Driver side of the dashboard | Interior lighting, cluster, windows, locking, audio |
| 43 to 63 | Under the hood, by the hinge on the driver side | Engine management, ABS and ESP, cooling fans, the larger MAXI fuses |
So when the chart says ABS is on 56, 59, 60 and 62, all four are under the hood and you never need to open the dash. When it lists numbers from two different bands, the system is fed from two panels and you check both.
A system with several fuses normally has a supply feed, a control feed and often a separate feed for its sensors, which is why finding one intact fuse does not clear that system. Check every number listed against it.
Fuse Designation Chart
The chart is alphabetical by system, so press Ctrl and F, or Command and F on a Mac, and type what has stopped working rather than reading every row.
| ABS | 56, 59, 60,62 |
| Airbag Warning Lamps | 41,42,45,49 |
| Active Head Restraint | 7 |
| Airbag / Side Airbag Control Unit | 45, 49 |
| Air Conditioner SE | 41,51 |
| Anti Theft Alarm | 8,9,41 |
| Automatic Heater System | 41 |
| Auxiliary Heater SE | 35 |
| Blower Motor (Heater / AC) | 30,41 |
| Brake Lights | 62 |
| Central Locking | 21, 22,32,57 |
| Central Locking Interior Switch | 41 |
| Cigar Lighter | 47 |
| COMAND | 64 |
| Convenience Locking | 8,9,21,22,32,33 |
| Courtesy Lights | 21,22 |
| Diagnostic Socket | 62 |
| Dipped Beam | 62,63 |
| Dome Lights / Interior Lights | 3,9 |
| E-Call / TeleAid | 40,44 |
| Electronic Stability Program ESP | 55,56,57,59,60,62 |
| Engine Electronics | 48,53,54 |
| Engine Emergency Stop | 53,54 |
| Engine Fan | 51 |
| Engine Residual Heat System | 30,41,51 |
| Fanfare | 43 |
| Fog Lamps | Electronic |
| Fog Tail Light | electronic |
| Fuel Filler Flap Unlocking | 15 |
| Fuel Pump | 4 |
| Garage Door Opener | 9 |
| Glove Compartment Light | 47 |
| Hazard Warning Flashers | 41 |
| Headlamp Flasher | Electronic |
| Headlamp Range Adjustment | 51 |
| Headlamp Washer System | 63 |
| Heated Rear Window | 10,41 |
| High Beam Indicator Lamp | electronic |
| Instrument Cluster | 42 |
| Language Control System | 13,16 |
| License Plate Illumination | Electronic |
| Locking Check Back | Electronic |
| Low Beam | 62,63 |
| Main Beam, M.B. Indicator Lamp | Electronic |
| Makeup Mirror | 9 |
| Mirror Adjustment | 21,22,63 |
| Automatic Dimming Mirror | 9,21 |
| Mirror Heater | 21,22 |
| Mirror Folding Feature | 21,22,63 |
| Multicontour Backrest | 13,19 |
| Multifunction Steering Wheel | Electronic |
| Navigation System | 64 |
| Number Plate Light | Electronic |
| Parking Lamps Tail Lamps | Electronic |
| Parktronic System | 13,41 |
| Power Socket, Trunk | 12,20 |
| Front Power Windows | 21,22 |
| Rear Power Windows | 21,32,33 |
| Radio | 64 or 36 |
| Rain Sensor | 9 |
| Rear Fog Light | Electronic |
| Rear Head Release | 41 |
| Rear Windscreen Wash System | 14,41 |
| Remote Trunk Trunk Release | 8,21 |
| Reversing Lamps | Electronic |
| Driver Seat Adjustment | 2,21,27, 29 coupe |
| Passenger Seat Adjustment | 1,22,38, 34 coupe |
| Seat Heater | 25,41 |
| Sound System | 26 |
| Start Enable | 31,52,57 |
| Steering Lock | 31 |
| Steering Wheel Adjustment | 2,21,27, Coupe 29 |
| Rear Window Sun Blind | 20,41 |
| Switch Illumination | 9,21,22,32,33,41,50 |
| Tele Aid/E Call | 40,44 |
| Telephone Systems | 13,16,40,44,36 |
| Television | 3 |
| Sunroof Sliding Roof | 9 |
| Trailer Lights | 17 |
| Trailer Power Supply | 18 |
| Transmission Electronics | 55,58,61 |
| Turn Signal Indicator Lamp | Electronic |
| Water Pump AMG | 5 |
| Windshield Washer Pump | Electronic |
| Windscreen Wipers | 46 |
Fuse Color and Amperage on the W203
Mercedes color codes its fuses so you can read the rating without pulling the fuse right out. One catch before you match a fuse by color: the standard blade fuses and the larger MAXI fuses reuse the same colors at different ratings. Red is 10 A as a blade fuse and 50 A as a MAXI. Blue is 15 A as a blade and 60 A as a MAXI. Judge by the physical size first, then the color.
Standard Blade Fuses
| Color | Rating |
|---|---|
| Beige | 5 A |
| Brown | 7.5 A |
| Red | 10 A |
| Blue | 15 A |
| Yellow | 20 A |
| White | 25 A |
| Green | 30 A |
MAXI Fuses, the Larger Cartridge Type
| Color | Rating |
|---|---|
| Amber | 40 A |
| Red | 50 A |
| Blue | 60 A |
Fuses do not wear out. They blow because current exceeded the rating, so a blown fuse is a symptom rather than the fault.
- Blew once and the new one holds. An event. Note it and move on.
- The new one blows the instant you fit it. A dead short to ground in that circuit, often where a harness crosses a bulkhead or runs near something that moves.
- Blows after a few minutes or only under load. A motor or component drawing too much as it heats up.
Never fit a larger fuse. The fuse protects the wire, not the component. Put a 30 A where a 15 A belongs and the wiring becomes the fuse, which is how harnesses melt. Keep a fuse assortment and a test light in the car instead.
When the Fuse Is Fine and the Circuit Is Still Dead
A W203 is early enough that plenty of circuits still run through conventional relays, but the SAM modules already control a good number of them. So the fuse can test good, the bulb or motor can be good, and nothing happens because a SAM output has failed.
No scan tool can see a blown fuse. Nothing on the diagnostic socket can. What a scan tool does is read the SAM and report whether that channel shows an open circuit, an overload or a dead output, which is the difference between replacing a part and replacing a module.
The UCAN-II Pro reads the front and rear SAM along with every other module on the W203, so you can tell a dead output from a dead component. It covers nearly everything XENTRY does apart from online VIN coding.
A SAM with a burnt output is a board level repair rather than automatically a new module. Module Medics repairs front and rear SAM units, which keeps your original part number and avoids the coding a replacement needs.
Related Reading
Understanding the SAM Module
What a failed SAM output looks like when every fuse tests good.
C-Class W204 Fuse Chart
The generation after this one, with three panels and a different numbering scheme.
W220 S-Class and CL Fuse Chart
The same era of Mercedes electrics in the big car.
SL R230 Fuse Chart
Four panels, and the roadster specific circuits.
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
We sell the UCAN-II Pro. The function comparisons above come from each manufacturer’s own documentation so you can check them yourself.
My trunk motor went out so i got the replaycemnt the only thing is the wiring how to connect it back.
Wow,thank you so much..I was looking every where for this. Just wondering do you have a relay diagram,need to find ac relay..
I have a 2005 c230k