Component description for trailer recognition control unit - GF31.19-P-4050CA
MODEL 207.3/4 with CODE 550 (Trailer coupling)
Model 207.3
Location
The trailer recognition control unit is secured in the luggage compartment behind the right luggage compartment lining.
Model 207.4
Location
The trailer recognition control unit is located in the right of the trunk on the trunk floor.
Task
The trailer recognition control unit has the following tasks:
- Reading in of sensors, pickups and signals
- Evaluation of input factors
- Monitoring of ball neck lock
- Trailer recognition
- Trailer consumer actuation
- 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 status of the trailer hitch locking switch (S142) is read in via a direct line by the trailer recognition control unit.
Interior CAN
The signals are read in by the trailer recognition control unit via the interior CAN.
The functions that use these signals are described in the individual function descriptions (see block diagram or function schematic).
Evaluation of input factors
The input factors are evaluated by the microprocessor and the corresponding components are actuated.
Monitoring of ball neck lock
The trailer recognition control unit monitors the correct seating of the mechanically-hinged ball neck. For this purpose, the trailer recognition control unit reads in the status of the trailer hitch locking switch directly. If the ball neck is not in the correct position, this is indicated by a flashing light-emitting diode (LED) in the trailer hitch unlocking device (A63) (on the left inside 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 warning message appears in the multifunction display (A1p13) of the instrument cluster.
Trailer recognition
By means of current monitoring of the "left turn signal" and "brake lights" outputs the trailer recognition control unit detects whether the supply line of the trailer is plugged in or not. When one of the two loads is recognized, the trailer is deemed to be recognized.
The trailer recognition control unit sends the trailer recognition status via the interior CAN.
Trailer consumer actuation
The trailer recognition control unit actuates the following trailer components over the trailer socket (X58):
- Brake light
- Rear fog lamp
- Backup lamp
- Turn signal lamp
- Taillight and license plate lamp
- Trailer power supply, circuit 30g
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 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 via the interior CAN, the trailer's taillights are actuated.
Consumer shutoff
If a corresponding request is issued by the rear SAM control unit with fuse and relay module (N10/2), circuit 30 to the trailer socket will be switched off. The lighting system of the trailer is not actuated.
| Trailer recognition control unit wiring diagram | PE31.19-P-2101-97EAA |