Mercedes-Benz C-Class Manuals

Mercedes Benz C-Class (W204) 2007 - 2014 Training Manual: Trailer Hitch (SA Code 550)

System description

A mechanical swivel trailer hitch is used in model series W204.

Towing capacity:

not braked 750 kg
braked 1800 kg

Tongue weight capacity: 50 kg

It locks in the swiveled-in and swiveled-out position mechanically.

The lock can be released mechanically via the operating unit, which is located on the left in the trunk, and the ball neck can be swiveled in and out.


  1. Light emitting diode
  2. Operating unit

Mercedes Benz C-Class. Trailer Hitch (SA Code 550)

Procedure for swiveling in or out: Move operating unit into the adjustment position by pulling.

The ball neck is moved out of the secure detent position by twisting it.

Latch the ball neck securely until the LED goes out.

Error situation: If it is "not securely latched in" this is indicated by a flashing light emitting diode, which is integrated into the operating unit.

In this case, when the ignition is switched on the driver information "Trailer hitch - check lock" appears in the instrument cluster.

Mercedes Benz C-Class. Trailer Hitch (SA Code 550)

Component description

Trailer recognition control unit (N28/1)

The trailer recognition control unit (N28/1) (SA) is installed on the right side of the trunk.


  • Trailer recognition
  • The trailer recognition control unit (N28/1) recognizes, by monitoring the current of the outputs for "left turn signal" and "brake light", whether or not the power supply for a trailer is plugged in. If one of the two loads is detected, the trailer is deemed recognized.
  • Actuation of the trailer lighting
  • Monitoring of the ball neck lock
  • Bulb monitoring of the trailer
  • Shutoff of circuit 30 at the trailer socket, if consumer shutoff is active, by the on-board electrical system management in the rear SAM control unit with fuse and relay module (N10/2). The shut-off element is seated in the trailer recognition control unit (N28/1).

Mercedes Benz C-Class. Trailer Hitch (SA Code 550)


N28/1 Control unit for trailer recognition

Chassis Versions

The C-Class in model series 204 is available in four suspension versions.

1. Basic suspension

The basic suspension (Agility Control suspension) is distinguished by the comfort-oriented tuning of the suspension components, which at the same time meets the high demands for vehicle responsiveness.

The classic tuning conflict in the suspension can largely be resolved in the new C-Class by using an amplitude-selective damping system (SDD - Stroke Dependent Damping).

2. Sports suspension

In addition to the basic suspension, there is also a sports suspension available for the new C-Class. The sports suspension differs from the basic suspension firstly by a level lowered by -15 mm. Furthermore, as a result of a stiffer damper tuning, the sprung mass vibrations are dampened to a greater extent, the alternate roll support is increased in comparison to the basic suspension due to stiffer stabilizer bars. As for the basic suspension, the front axle and rear axle dampers are designed as amplitude-selective dampers (SDD). This also ensures a much greater ride comfort for sports suspensions.

3. Rough road suspension

The rough road suspension of the new C-Class is also designed with a view to comfort with a vehicle level that is 15 mm higher than the basic suspension.

The higher driving level is achieved by a longer damper tube with spring cups set higher for the front axle suspension strut and longer rear axle springs. The dampers of the rough road suspension are also equipped with amplitudeselective dampers, adapted to the handling characteristics of the basic suspension.

4. Advanced Agility package (available from September 2007)

Continuously variable damping technology is used for the very first time in the C-Class as part of the Advanced Agility package. The system, which is unusual for this vehicle category, takes into account in particular the demands for a very high degree of responsiveness, without neglecting the comfort requirements, for which the brand is known.

Information for Service

Any necessary leveling is performed on all suspension versions by means of springs of different lengths.


    Front Axle

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