MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
Last updated:
In this guide (4 sections)
Watch: Fuse Location Mercedes-Benz S-Class W221 2006 to 2013
- F32/3, prefuse box, engine bay. The big MAXI fuses that feed everything else. If several unrelated systems are dead at once, start here rather than chasing each one.
- N10/1, front SAM, engine bay. Engine management, lighting, wipers, and most front end circuits, with the relays alongside.
- F1/6, interior, right side of the dash. Passenger side interior circuits.
- F1/7, interior, driver side of the dash. Driver side interior circuits, the cluster and the steering column.
- P32/4, prefuse box behind the dash, passenger side. Secondary supply feeds.
- N10/2, rear SAM, boot. Seats, boot lid, amplifier, rear lighting, and the boot power outlet.
Rule of thumb on a W221: one dead item means a fuse in the SAM panel for that end of the car. Several dead systems at once means a prefuse, because a prefuse feeds a whole panel downstream of it.
Where the Fuse Boxes Are on a W221
| S-Class W221 (2007-2013) S320 CDI, S350, S450, S500, S550, S420 CDI, S600 |
CL-Class C 216 (2006-2014) CL 500, CL 600, CL 63, CL 65 AMG |
- Prefuse Box in the Engine Bay – F32/3
- Fuse Box in the Engine Bay – Front SAM Control Unit – N10/1
- Fuses on the right side of the dash F1/6
- Fuses in the Left side of the dash F1/7
- Prefuse Box Hidden behind the dash, passenger side. P32/4
- Battery Fuse – Backup – F37
- Fuses in the trunk – Rear Sam Control Unit – N10/2
Prefuse Box, Engine Bay, F32/3
| Fuse | Ampere Rating | Designation |
| F2 | 400 | Alternator |
| F3 | 150 | Electrohydraulic Power Steering A91/1 or glow time output stage N14/3 |
| F4 | No fuse | Interior Prefuse box F32/4 |
| F5 | 100 | AAC with integrated control, additional fan motor M4/7 |
| F6 | 150 | Front SAM control unit with fuse. Relay module N10/1 |
| F7 | 40 | ESP Control Unit, Brake System |
| F8 | 25 | ESP Control Unit, Brake System N30/6 |
| F9 | 30 | Front SAM control unit N10/1 |
| F10 | – | Not used |
Relays, Engine Bay, Front SAM Control Unit N10/1
Fuses Engine Bay – Driver Side N10-1 Front SAM Control Unit
| Relay | Purpose |
| A | Air Pump Relay |
| B | Air Suspension Compressor Relay |
| C | Engine terminal 87 |
| D | Relay 15 -Terminal |
| R | Terminal 87 relay |
| F | Horn Relay |
| G | 15R Relay |
| H | Starter – Circuit 50 relay |
| J | Starter – Circuit 15 |
| K | Wiper park heater relay |
Fuses, Engine Bay, Front SAM Control Unit N10/1
| FUSE | AMPERE RATING | PURPOSE |
| F20 | 10 | Â Control Unit N3/9 or N3/10 |
| F21 | 20 | Circuit 87 – Fuel Pump Relay |
| F22 | 15 | Connector sleeve |
| F23 | 20 | Rear SAM Control Unit Fuse Box |
| F24 | 25 | CDI Control Unit N3/9 |
| F25 | 7.5 | Instrument Cluster – Dashboard |
| F26 | 10 | Left headlight – lamp unit |
| F27 | 10 | Right Headlight – lamp unit |
| F28 | 7.5 | EGS Unit Transmission control unit. |
| F29 | 5 | Rear fuse box and relay module, Rear SAM N10/2 |
| F30 | 7.5 | Fuel System Control Unit, Engine Control Unit N3/9 N3/10 N118 |
| F31 | 5 | Refrigerant Compressor |
| F32 | 15 | Transmission oil pump control unit N89 |
| F33 | 5 | ESP Control Unit, Battery Management, Power Electronics |
| F34 | 5 | Braking System N30/6 |
| F35 | 5 | Electric parking brake -A13 |
| F36 | 10 | Data link connector – 16 PinX11/4 |
| F37 | 7.5 | EIS Control Unit N73 |
| F38 | 7.5 | CGW Central Gateway control unit, Audio, Sound |
| F39 | 7.5 | Instrument cluster |
| F40 | 7.5 | Upper control panel N72/1 |
| F41 | 30 | Wiper motor M6/7 |
| F42 | 30 | Master wiper motor M6/6 |
| F43 | 15 | Front cigar lighter with ashtray illumination |
| F44 | – | Unused |
| F45 | 5 | Power electronics pump M13/8 |
| F46 | 15 | ABC Control Unit N51/2 or AIRMATIC N51 |
| F47 | 15 | Steering column adjustment motor up or down |
| F48 | 15 | Steering column adjustment motor in / out |
| F49 | 10 | Steering column N80 |
| F50 | 15 | AAC Unit N22/1 |
| F51 | 5 | COMAND Display |
| F52A | 15 | Horns |
| F52B | 15 | Horns |
| F53 | – | Unused |
| F54 | 40 | Air Recirculation AC |
| F55 | 60 | Electric Air Pump |
| F56 | 40 | AirMatic Compressor Pump A9/1 |
| F57 | 30 | Wiper Heater R2/10 |
| F60 | 5 | Power Steering A91-1 |
| F61 | 7.5 | SRS Airbag Restraint System N2/7 |
| F62 | 5 | Night View Assist N101 |
| F63 | 15 | Fuel Filter Sensor B76/1 |
| F64 | 10 | NECK PRO Head Restraint Solenoids Y24/12 – Driver, Y24/13-Passenger |
| F65 | 15 | Outlet in the glove box |
| F66 | 7.5 | DTR Unit A89 |
Interior Fuses, Right Side of the Dash, F1/6
| Fuse Number | Ampere Rating | Â Designation |
| F70 | 40 | Door Control Unit – Right N69/2 |
| F71 | 15 | Keyless Go Control Unit N69/5 |
| F72 | 7.5 | Pyrotechnical Separator K88 |
| F73 | 5 | Emergency Call System Control Unit |
| F74 | 30 | TLC Control Unit |
| F75 | 10 | Battery Management |
| F76 | 15 | Vacuum pump relay |
| F77 | 50 | Sound Amplifier A2/13 |
| F78 | 25 | AdBlue Relay/ Additional Fan/ Charge Air Cooler Circulation Pump |
| F79 | 7.5 | Alarm H3/1 |
| F80 | 40 | Door Control Unit – Left Door N69/1 |
| F81 | 30 | Rear control unit CL model
Rear door control unit S Class |
| F82 | 30 | Rear door control unit |
| F83 | 30 | Intelligent Servo Unit. Direct Select |
| F84 | 20 | Sound Proceeding Unit A2/69 |
| F85 | 10 | Â Illumination for Door Sills |
| F86 | – | Not used |
| F87 | – | Not used |
| F88 | – | Not used |
| F89 | – | Not used |
| F90 | 20 | Heater unit |
| F91 | 5 | Front SAM unit |
Interior Fuses, Driver Side of the Dash, F1/7
| Fuse Number | Ampere Rating | Designation |
| F92 | 40 | Left front seat N32/1 |
| F93 | 7.5 | Weight sensing system N2/13 |
| F94 | 5 | Camera |
| F95 | – | Spare |
| F96 | 5 | TPM RDK Unit N88 |
| F97 | 7.5 | DVD Player |
| F98 | – | Spare |
| F99 | 7.5 | COMAND |
| F100 | 5 | Media Interface N125/1 |
| F101 | 10 | Rear Displays Left A40/5 RightA40/6 |
| F102 | 40 | Right front seat N32/2 |
| F103 | 7.5 | ESP Electronic Stability Program |
| F104 | 40 | Audio Radio Tuner |
| F105 | – | Not used |
| F106 | 5 | Navigation / TV Tuner/ Toll Collection |
| F107 | 5 | HD Tuner N87/8, Audio Broadcasting N87/3, SDAR Sirus Unit |
| F108 | 5 | Rear A/C N22/4 |
| F109 | 15 | Rear Air Conditioner Blower Motor N29/2 |
| F110 | 7.5 | Rear Backrest control Unit N32/20 N32/21 |
| F111 | 5 | RCP Control Unit N72/2 |
| F112 | 5 | Fuse box, Front SAM |
| F113 | 5 | DC Converter |
| F114 | – | Not used |
-
Prefuse Box Behind the Dash, Passenger Side, P32/4
| Fuse Location | Ampere Rating | Purpose |
| F3 | 150 | Rear SAM control unit N10/2 |
| F4 | 150 | Heated Windshield, DC Converter, ECO start/stop function |
| F5 | 40 | Vacuum Pump |
| F6 | 80 | Right dashboard fuse box F1/6 |
| F7 | 150 | Heater booster R22/3 |
| F8 | 80 | Front SAM module N10/1 |
| F9 | 80 | Left dashboard fuse box F1/7 |
| F10 | 150 | Rear SAM N10/2 |
-
Battery Backup Fuse, F38
Fuse 38 is a 5-ampere fuse for the additional auxiliary battery G1/7, EZS control unit N73, and Front SAM control unit.
Which Fuses the W221 Uses
Standard blade fuses are used in the S-Class.
-
Fuses in the Boot, Rear SAM Control Unit N10/2
Fuse Ampere Rating Designation F115 50 Rear window heater F116 10 Power electronic pump F117 15 Rear cigar outlet F117 30 Fuel Pump F118 15 AC Compressor/ Power electronics pump/ fuel pump F119 7.5 Front central unit A40/9 F120 – Not used F121 10 Audio radio tuner F122 7.5 COMAND A40/3 F123 40 Emergency tension retractor – Right front A76/1 F124 40 Emergency tensioner retractor – left front A76 F125 5 Voice Control VCS N41/3 F126 25 Overhead control panel N70 F127 30 Pneumatic pump seat control M40/1, Seat pneumatic pump M40, Lumbar pmp M25/1 F128 25 Fuel pump N118 F129 25 Universal portable cell phone control unit UPCI N123/1 F130 30 Parking brake – Electric A13 F131 7.5 Rear window antenna amplifier A2/12 F133 5 Rear camera B84/3 F134 15 Rear trunk outlet socket X58/12 F135 7.5 Radar sensor / parktronic PTS N62 F136 7.5 AdBlue N118/5 F137 7.5 Rear Camera B84/3 F138 5 TV/tuner/emergency/ call/navigator F139 15 Rear backrest refrigerator A39/1 F140 15 120 outlet socket, rear cigarette lighter outlet F141 5 Rear camera N66/2 F142 7.5 Video and radar sensor N62 F143 25 Rear seat N25/6 F144 25 Rear seat N25/6 F145 20 Rear trailer hitch socket – 13-pin type – X58 F146 25 Trailer N28/1 F147 – Spare F148 25 Panoramic sliding sunroof F149 25 Panoramic sliding sunroof A98 F150 7.5 TV Tuner F151 20 Trailer F152 25 AC Converter from DC N24/3 F153 – Not used Relays in the Boot, Rear SAM Control Unit N10/2
Relay Purpose of relay M Circuit 15 N10/2 N Terminal 15R O Power outlet relay R Cigar lighter relay S Fuel Pump
Printed Fuse Charts Supplied With the Car
Printed fuse charts that come with the car.
- It blew once, and the new one holds. That was an event. Note it and move on.
- The new one blows the instant you fit it. There is a dead short to ground in that circuit, often where a harness crosses a bulkhead or passes near something that moves.
- It blows after a few minutes or only under load. A motor or component is drawing too much as it heats up. The fuse is protecting you from a failing part.
Never fit a larger fuse. The fuse is sized to protect the wire, not the component. Put a 30 A where a 15 A belongs, and the wire 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
This is the W221 trap. Most circuits on this car are not switched by a relay you can swap. They are switched by an output inside the front or rear SAM, so the fuse can be good, the bulb or motor can be good, and nothing happens because the SAM output has failed.
No scan tool can see a blown fuse. Nothing that plugs into the diagnostic socket can. What a scan tool does is read the SAM and tell you whether the module reports an open circuit, an overload or a failed output on that channel, which is the difference between replacing a part and replacing a module.
When a fuse is intact but an electrical component still does not work, a full-system diagnostic scanner can help retrieve fault codes from supported control modules. The YOUCANIC UCAN-II Pro provides system-level diagnostics for supported Mercedes-Benz vehicles and can help identify electrical faults that require further investigation. Available modules and diagnostic functions depend on the vehicle’s configuration.
Related Reading
Understanding the SAM Module
The module behind most of the circuits on this chart.
SL R230 Fuse Chart
The same era of Mercedes electrics in the roadster.
W220 S-Class and CL Fuse Chart
The generation before this one, with a different panel layout.
C-Class W203 Fuse Locations
Fuse map and box photographs for the W203.
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.
