Component description for trailer recognition control unit - GF31.19-P-4050RF
MODEL 205, 253 with CODE 550 (Trailer coupling)
Shown: Model 205.0
Location
The trailer recognition control unit is located in the trunk in the spare wheel well.
Task
The trailer recognition control unit has the following tasks:
- Reading in of signals
- Evaluation of input factors
- Release, swivel and lock trailer hitch
- Monitoring of ball neck lock
- Trailer recognition
- Trailer consumer actuation
- Lamp failure indicator
- Emergency light function
- Consumer shutoff
Reading in of signals
The input factors are read in over the following connections:
- Direct line
- Interior CAN (CAN B)
Direct line
The signals from the following components are read via direct lines:
- Trailer hitch release (A63) (model 205)
- Fully electric trailer hitch swivel unit (A63/2) (model 253)
- Trailer hitch release switch (S62/24) (model 205)
- Trailer hitch switch (S142/2) (model 253)
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.
Release, swivel and lock trailer hitch
The ball neck of the trailer hitch can be swiveled in and out together with the trailer socket (X58) using the electromechanical swivel unit. This is done by actuating the trailer hitch release switch (model 205) or the trailer hitch switch (model 253).
By evaluating the signals from a Hall sensor in the electromechanical swivel unit, the trailer recognition control unit detects the current position of the ball neck.
The following components are integrated in the electromechanical swivel unit:
- Hall sensor for detecting position of ball neck
- Swivel motor for swiveling ball neck in and out
- Locking finger for ball neck lock
- Locking finger sensor for monitoring the ball neck lock
Monitoring of ball neck lock
The trailer recognition control unit monitors the correct seating of the electromechanically swiveling ball neck. For this purpose, the trailer recognition control unit evaluates the signals from the locking finger sensor in the electromechanical swivel unit. A ball neck that is not in a correct position is indicated by an LED in the trailer hitch release switch or in the trailer hitch switch flashing on and off. With circuit 15 ON, the trailer recognition control unit sends a corresponding signal via the interior CAN, electronic ignition lock control unit (N73) and the user interface CAN (CAN HMI) to the instrument cluster (A1). A corresponding warning message then appears in the multifunction display (A1p13) of the instrument cluster.
Trailer recognition
By means of current monitoring of the "left turn signal light" 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 via the trailer socket:
- 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 light sources on the trailer. Only faults in the general lamp path are detected. If a failure is detected, the trailer recognition control unit sends corresponding information via the interior CAN.
LED version trailer lighting: The minimum current for each lamp path must be I = 50 mA for reliable lamp failure detection. When this minimum current is dropped below the limit, 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 via the interior CAN, the taillights on the trailer are actuated via the trailer socket.
Consumer shutoff
With active consumer shutoff, triggered by the rear SAM control unit (N10/8), the trailer recognition control unit switches off circuit 30g at the trailer socket. The lighting system of the trailer is not actuated.
| Trailer recognition control unit wiring diagram | PE31.19-P-2101-97FBA |