Component description for trailer recognition control unit - GF31.19-P-4050CE
MODEL 204.0/2
with CODE (550) Trailer hitch
as of model year 2009
/YoM 08
MODEL 204.3 with CODE (550) Trailer hitch
MODEL 204.9 with CODE (550) Trailer hitch
Shown on model 204.0
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 the ball neck lock
- Actuation of 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 via the following connections:
- Direct line
- Interior CAN (CAN B)
Direct line
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
The trailer recognition control unit briefly energizes the outputs for "left turn signal" and "right turn signal" and uses the voltage level to determine whether the trailer's supply line is connected or not. If one of the two loads is detected, the trailer is deemed to have been recognized. This status is sent over the interior CAN.
Monitoring the 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. A ball neck that is not in a correct position is indicated by a flashing light-emitting diode in the trailer hitch release in the left of the luggage compartment.
At circuit 15 ON a corresponding signal is also sent over the interior CAN to the instrument cluster (A1) by the trailer recognition control unit.
A corresponding warning message is shown on the travel distance display (A1p7) (model 204.0/2/3/9 (except 204.077/277/375) without code (442) Comfort multifunction steering wheel) or in the multifunction display (A1p13) (with code (442) Comfort multifunction steering wheel, model 204.077/277/375) of the instrument cluster.
Actuation of the trailer lighting
The trailer recognition control unit actuates the following components for the trailer's lighting system over the trailer socket (X58):
- Taillights and license plate lamp
- Turn signal lamp
- Brake lights (as of 1.6.09 also adaptive brake lights)
- Rear fog light (without code (494) USA version)
- Reversing lamp
For vehicles with code (494) USA version, the turn signal lights and brake lights function are actuated over the same output. At simultaneous actuation the turn signal lights takes priority.
As of 1.6.09 the trailer recognition control unit is able to actuate trailer lighting in a light-emitting diodes (LED) version.
Trailer monitor (with code (551) Antitheft alarm system (ATA [EDW]))
The trailer recognition control unit monitors the trailer socket. As soon as a status change from "trailer recognized" to "trailer not recognized" occurs, 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 antitheft 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 the trailer recognition control unit sends a corresponding signal over the interior CAN.
Trailer lighting in LED version:
The minimum current for each lamp path must be I = 50 mA for reliable lamp failure detection. When this minimum current is dropped below a fault message appears in the travel distance display or the instrument cluster's multifunction display 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 via the interior CAN, the trailer's taillights are actuated.
Consumer shutoff:
When accordingly requested by the rear SAM control unit circuit 30 to the trailer socket is switched off.
| Trailer recognition control unit wiring diagram | PE31.19-P-2101-97FAA |