Connection between computer and car

The adapter for connecting the PC to the car is supplied with in total three extension units with various diagnostic connectors. All three cables feature the same connector at one of their ends through which the corresponding extension is connected to the diagnostic adapter.  

OBD connector

Cars manufactured around the year 1995 and later are using the 16-pin OBD-II diagnostic connector (see the picture). For this connector there is no danger of damage to the adapter due to wrong connection (cannot be pushed in the other way round).

16-pin OBD-II
connector

5-pin connector (models with single-point injection)

Skoda Favorit and older models of Seat Ibiza 1994 – 1999 cars are using a 5-pin diagnostic connector. In these cars it is necessary to dismantle the cover of the diagnostic connector and only then to connect the adapter connector. Also for this type of connector there is no danger of damage to the adapter due to wrong connection (cannot be pushed in the other way round).

5-pin diagnostic connector

Audi 2×2 connector

In older VW and Audi cars, using two 2-pin connectors, a cable with four conductors taken out separately is to be used. Attention is to be paid to the correct connection of the particular conductors. The black diagnostic connector serves for the power supply and it is recommended to verify the correct polarity of the powering voltage. The green-white conductor is to be connected to the +12V pin, the blue-white conductor to the car body. Reversed polarity causes the fuse of the diagnostic socket to be blown, but also a damage may happen to the adapter. This is why your  attention is to be paid to the connection of powering conductors.

The brown or white diagnostic connector includes the K and L data pins. The K pin connects to the green conductor of the diagnostic cable, the L pin connects to the blue conductor of diagnostic cable. Improper connection of the data conductors constitutes no a danger.   If more data diagnostic sockets (larger numbe of control units) are installed in the car it is always necessary to find the corresponding socket for the particular control unit (e.g. airbag, ABS, air conditioning, etc.) and connect the corresponding K data pin with the diagnostic cable green conductor. These auxiliary diagnostic connectors mostly have the L pin missing and, consequently, the diagnostic cable remains loose (not connected).

VW LT connector
Use extensions with separate pins and populate the connector pursuant to the table (depending on what control unit you want to communicate with).

Control unitGreen-white conductor
Power supply (+12V)
Blue-white conductor
Power supply (-, car body)
Green conductor
K data pin
Imobilizer3114
Engine control3114
OBD connector in a car (90° rotation)