What is and why do you need a matching block for a towbar

Cars manufactured before 2000 usually do not have problems connecting a trailer. It is enough to install the towbar, connect the electrical equipment through the socket and you can go. On modern cars, electronic control units (ECUs) are used, which control the power supply. Connecting additional consumers directly will throw an error. Therefore, for a secure connection, a matching block or smart connect is used.

What is Smart Connect

Modern cars are equipped with various electronic systems for greater comfort and convenience. It would take a huge amount of wires to fit all these systems together. To solve this problem, car manufacturers use CAN-BUS or CAN-bus. Signals only flow through two wires, being distributed through the bus interfaces. In this way, they are distributed to different consumers, including parking lights, brake lights, turn signals and so on.

If, with such a system, the electrical equipment of the towbar is connected, then the resistance in the electrical network will immediately change. The OBD-II on-board diagnostic system will indicate the error and the corresponding circuit. Other lighting fixtures may also malfunction.

To prevent this from happening, Smart Connect is installed. A separate wire is used for connection to the vehicle's 12V voltage. The device matches electrical signals without changing the load in the vehicle's electrical network. In other words, the on-board computer does not see the additional connection. The unit itself is a small box with a board, relays and contacts. This is a simple device that you can even make yourself if you want.

Functions of the matching block

The functions of the matching unit depend on the configuration and factory capabilities. The basic functions include the following options:

• turn signals on the trailer;
• fog lights control;
• deactivation of parking sensors while using the trailer;
• trailer battery charge.

Extended versions may have the following options:

• checking the status of the trailer connection;
• control of the left side light;
• control of the left fog lamp;
• anti-theft warning system ALARM-INFO.

When is the module needed and on which cars is it installed?

The smart connection is required if the vehicle has the following electronic systems:

• on-board computer with CAN-BUS Data system;
• function of electronic control of alternating voltage;
• multiplex wiring in the car;
• burned-out lamp detection system;
• Check Control system;
• LED lighting and low voltage power supply.

The following is a table of car brands and their models, on which it is mandatory to install a matching unit when connecting a trailer:

car brand	Model
BMW	X6, X5, X3, 1, 3, 5, 6, 7
Mersedes	The entire lineup since 2005
Audi	All Road, TT, A3, A4, A6, A8, Q7
Volkswagen	Passat 6, Amarok (2010), Golf 5 and Golf Plus (2005), Caddy New, Tiguan (2007), Jetta New, Touran, Toureg, T5
CITROEN	C4 Picasso, C3 Picasso, C-Crosser, C4 Grand Picasso, Berlingo, Jumper, C4, Jumpy
Ford	Galaxy, S-max, C-max, Mondeo
Peugeot	4007, 3008, 5008, Boxer, Parthner, 508, 407, Expert, Beeper
Subaru	Legacy Outback (2009), Forester (2008)
Volvo	V70, S40, C30, S60, XC70, V50, XC90, XC60
Suzuki	splash (2008)
Porsche Cayenne	c 2003
Jeep	Commander, Liberty, Grand Cherokee
KIA	Carnival, Sorento, Soul
Mazda	Mazda 6
Dodge	Nitro, Caliber
Fiat	Grande Punto, Ducato, Scudo, Linea
Opel	Speedster, Astra C, Frontera, Insignia, Astra H, Corsa
Land Rover	all Range Rover models since 2004, Freelander
Mitsubishi	Outlanders (2007)
Skoda	Yeti, 2 of, Fabia, Superb
Seat	Leon, Alhambra, Toledo, Altea
Chrysler	Voyager, 300C, Sebring, PT Cruiser
Toyota	RAV-4 (2013)

Connection algorithm

As already mentioned, the matching unit is connected directly to the battery contacts. The connection diagram can be seen in the following figure.

To connect, you need to do the following:

• remove loading panels;
• have a set of wires with the required cross-section available;
• check running and brake lights;
• mount the unit according to the connection diagram;
• connect the wires to the unit.

Smart Connect views

Most smart connect blocks are universal. There are a lot of manufacturers. Such brands as Bosal, Artway, Flat Pro are very easy to install, but not all cars accept universal blocks. If the vehicle's ECU is equipped with an auto-towing trailer function, the original unit will be required. Also, Smart Connect often comes with a towbar socket.

Unikit matching block

The Unikit complex is very popular with car owners for its reliability, versatility and ease of use. It correctly connects the electrician of the towing vehicle and the vehicle. Unikit also reduces the load on the car's on-board network, protects against overload, and tests the connection for failures. In the event of a power surge, it will only be necessary to replace the fuse. The rest of the wiring remains intact.

Among the advantages are the following:

• trailer electrics testing;
• prescribing the original system;
• disabling parking sensors and a rear-view camera;
• reasonable price - about 4 rubles.

The connected trailer is part of the vehicle. Each driver must monitor the correct operation of all systems, including the trailer signals. Smart Connect is the device that is required for all electronics and signals to function correctly. Its use will prevent possible errors and failures when connecting.