Component Description For Trailer Recognition Control Unit - GF31.19-P-4050LF
Model 222
with CODE 550 (Trailer coupling)
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
- 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 signals from the following components are read via a direct line:
- Trailer hitch switch (S143/3)
- Unlocking trailer hitch (A63)
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. To this end, the status of the trailer hitch switch is read in directly. A ball neck that is not in a correct position is indicated by an LED in the trailer hitch release flashing on and off. At circuit 15 ON, a corresponding signal from trailer recognition control unit is also sent over the interior CAN, electronic ignition lock control unit (N73) and the user interface CAN (CAN HMI) to the instrument cluster (A1). A warning message appears in 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. This status is sent 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
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 over the interior CAN.
LED version trailer lighting: The minimum current for each lamp path must be I = 50 mA for reliable lamp failure detection. If this minimum current is not reached, a fault message appears in 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 requested by the rear SAM control unit (N10/8), circuit 30g to the trailer socket is switched off. The lighting system of the trailer is not actuated.
| Trailer recognition control unit wiring diagram | PE31.19-P-2101-97SEA |