Connecting a towbar socket to a car - different ways and step-by-step instructions

To easily connect the towbar socket to a car with a digital bus, use a special device: a matching unit or Smart Connect (smart connector). Its options are the correct control of lamps without disrupting the operation of the basic circuits of the car, such as ABS, ESP and other electronic assistants.

Operating a trailer with non-working lighting devices is prohibited by Russian traffic rules. Therefore, it is not enough just to equip your car with a tow hook, you need to connect the towbar socket to the car.

Connector types

GOST 9200-76 was the main standard in the USSR, which established standards for the electrical connection of trailers to cars and tractors of that time that were uniform for all industries. It determines that all vehicles manufactured by the Soviet industry are equipped with the same seven-pin connectors.

After the appearance on the domestic market of a large number of cars and trailers of foreign production, the complete interchangeability of auto sockets was lost. Foreign cars are equipped with tow hitches (drawbars, or towbars) with electrical connections often of different types.

Today in operation you can find compounds of the following varieties:

• seven-pin connector of the "Soviet" type (according to GOST 9200-76);
• 7-pin euro connector (has a difference in the wiring section and wiring of the 5th and 7th pins);
• seven-pin (7-pin) American-style - with flat pins;
• 13-pin with separation of positive and negative tires;
• 15-pin for heavy cargo trailers (has lines for connecting the reverse indication from the trailer to the tractor driver).

Non-standard types of connectors are used in addition to the base one for connecting other electrical circuits (rear-view cameras, on-board circuits of a cottage trailer, and the like).

Ways to connect the towbar connector

The growth in the number of towed devices is due to the popularity of such types of recreation as car travel with campers, ATVs or jet skis, and large boats. Trailers from different manufacturers are equipped with different types of sockets, so you can connect the towbar to the car's wiring in different ways.

regular method

The simplest method that does not require intervention in the electrical circuit. You need to buy a set of adapters that are put on the factory taillight connectors. They are equipped with conclusions on the TSU.

Such kits can be selected to connect the towbar socket to the VAZ car of most models produced today: Largus, Grant, Vesta, Kalina, Chevrolet Niva.

Universal way

The wiring diagram for the towbar socket of a car is shown in the figure:

Wiring diagram for towbar socket

This is how the electrical circuits of the tractor and trailer are connected when the lighting equipment is not controlled by the controller. The wires are attached to the "chips" of the rear lights with special clips or by soldering.

Pinout of a 7-pin socket

The seven-pin towbar socket diagram of a passenger car is shown in the figure:

Socket with seven pins

Here the pinout (the correspondence of individual contacts to specific circuits) is as follows:

1. Left turn signal.
2. Rear fog lights.
3. "Minus".
4. Right turn signal.
5. Reverse indicator.
6. Stop.
7. Room lighting and dimensions.

You can connect all the wiring to one of the blocks, with the exception of the "turn signals", which must be connected to each side separately.

13-pin socket device

Connection diagram of the towbar socket to the car via the 13-pin connector:

Wiring diagram for towbar socket

There are adapters with which you can connect a 7-pin plug to a 13-pin socket.

15-pin connector design

15-pin connections are very rare on passenger vehicles, mostly on US-made heavy pickups or SUVs. The scheme of the towbar socket of a passenger car of this type in the figure:

15 pin connections on passenger vehicles

Its installation includes a lot of control buses with feedback, so it is best to consult an electrician for the correct operation of all circuits.

Step-by-step connection instructions

Connecting the towbar socket to the car with your own hands is recommended to be done without cutting the standard wires, but using intermediate connecting blocks, as when installing factory adapters.

You need to purchase the necessary materials:

• the connector itself with a protective cover;
• electrical pads of a suitable design;
• cable with colored conductors with a cross section of at least 1,5 mm²;
• hose clamps;
• protective corrugation.

Scheme of work:

1. Cut a piece of cable to the desired length with a margin for finishing the ends.
2. Remove insulation and tin wire tails.
3. Pass the cable inside the corrugated sleeve.
4. Unsolder the contacts in the socket housing, referring to the diagram of the car towbar socket.
5. Attach the wires to the rear light connectors, also checking their order.
6. Isolate all connections and connect the pads to the vehicle lighting connectors.
7. Lay the harness to the installation site on the towbar, fix and close the holes in the body with plugs.

It is better to use silicone sealant to isolate the cable entries into the socket and connectors.

Connection via matching block

The on-board electrical circuits are often controlled by a microprocessor circuit using a digital multi-bus (can-bus system). Such a system makes it possible to reduce the number of individual wires in bundles to two cables and to carry out operational control with fault diagnosis.

The disadvantage of digital control will be the impossibility of connecting the towbar socket of a passenger car, which is familiar to garage masters, directly to the network by inserting additional loads into the factory wiring. After all, additional consumers in the form of trailer bulbs will increase the consumed currents by almost two times, which will be determined by the control controller as damage. The system will consider these circuits as faulty and block their power supply.

To easily connect the towbar socket to a car with a digital bus, use a special device: a matching unit or Smart Connect (smart connector). Its options are the correct control of lamps without disrupting the operation of the basic circuits of the car, such as ABS, ESP and other electronic assistants.

The scheme for connecting a towbar to a car using a smart connector may vary depending on the type of device and the type of connector (7 or 13 pin). In summary, it looks like this:

See also: Autonomous heater in a car: classification, how to install it yourself

Smart connect

The price of the device with installation is from 3000 to 7500 rubles. It pays off in that it will save the car from much more expensive repairs, if without it the “brains” of the on-board network controller burn out from overload.

In the list of cars where the use of a smart connector is necessary:

• all models of Audi, BMW, Mercedes;
• Opel Astra, Vectra, Korsa;
• Volkswagen Passat B6, Golf 5, Tiguan;
• Skoda Octavia, Fabia and Yeti;
• Renault Logan 2, Megan.

The smart connector must be installed on cars of almost all Japanese brands.

Connecting the wires of the towbar socket