Trailer recognition control unit component description - GF31.19-P-4050LE
MODEL 221.0/1 with CODE (550) Trailer hitch as of Model Year 2009/modification year 08
Location
The trailer recognition control unit is located in the trunk behind the right luggage compartment lining.
Task
The trailer recognition control unit has the following tasks:
- Reading in of sensors, pickups and signals
- Evaluation of input factors
- Trailer recognition
- Monitoring of ball neck lock
- Controls the trailer lighting
- Trailer monitor (with code (551) Antitheft alarm system (ATA [EDW]))
- Lamp failure indicator
- Emergency light function
- Consumer shutoff:
Reading in of sensors, pickups and signals
The input factors are read in with the following connections:
- Direct line (as of 1.6.09)
- Interior CAN (CAN B)
Direct line (as of 1.6.09)
The signals from the following components are read via a direct line:
- Unlocking trailer hitch (A63)
- Trailer hitch lock switch (S142)
Interior CAN
The signals are read in by the trailer recognition control unit via the interior CAN.
The functions resulting therefrom are described in the corresponding function descriptions (see block diagram or function schematic).
Evaluation of input factors
The input factors that have been read in are evaluated by the integrated microprocessor and the relevant components are then actuated.
Trailer recognition
By means of current monitoring of the "Left flasher" and "Right taillight" outputs the trailer recognition control unit recognizes whether the supply line of the trailer is plugged in or not. If one of the two loads is detected, the trailer is deemed to have been recognized. In addition the status of the "Left taillight" is evaluated. This status is sent to the interior CAN.
Monitoring of ball neck lock
The trailer recognition control unit monitors the correct seating of the mechanically-hinged ball neck. To this end, the status of the trailer hitch lock switch is read-in directly. If the ball neck is not in a correct position, this is displayed by the flashing of an LED in the unlocking device of the trailer hitch (in left of trunk). At circuit 15 On a corresponding signal is also sent over the interior CAN to the instrument cluster (A1). A corresponding warning message appears in the multifunction display (A1p13) of the instrument cluster.
Controls the trailer lighting
The trailer recognition control unit actuates the following components of the trailer via the trailer hitch socket, 13-pin (X58):
- Taillights and license plate lamp
- Turn signal lamp
- Brake light (as of 1.6.09 also adaptive brake light)
- Rear fog light (without code (494) USA version)
- Reversing lamp
On vehicles with code (494) USA version the functions of turn signal and brake light are actuated via the same output. At simultaneous actuation the turn signal takes priority.
As of 1.6.09 the trailer recognition control unit is able to actuate the trailer lighting in a light-emitting diodes (LED) version.
Trailer monitor
(with code (551) Anti-theft alarm system (ATA [EDW]))
The trailer recognition control unit monitors the trailer socket. As soon as a status change takes place from "Trailer recognized" to "Trailer not recognized", the trailer recognition control unit transmits a corresponding signal via the interior CAN to the rear SAM control unit with fuse and relay module (N10/2), which as a result of this outputs an anti-theft alarm system alarm.
Lamp failure indicator
The trailer recognition control unit monitors the function of the trailer lamps. However, only faults in the general lamp path are recognized. If a failure is detected, a corresponding signal is sent to the interior CAN.
Trailer lighting in an LED version:
For safe lamp failure recognition the minimum for each lamp path must be I = 50 mA. If this minimum current is dropped below a fault message appears in the multifunction display of the instrument cluster, although the function of the trailer lighting is OK.
Emergency light function
If the trailer recognition control unit fails or if there is a corresponding request placed onto the interior CAN, the trailer's taillights are actuated.
Consumer shutoff:
With a corresponding request through the rear SAM control unit with fuse and relay module circuit 30 to the trailer socket is switched off.
| Trailer recognition control unit wiring diagram | up to 31.5.09 | PE31.19-P-2101-99SAA | |
| As of 1.6.09 | PE31.19-P-2101-99SAB |