Function Check for VAGCOM Adapter

Hello everyone

After Georg and Achim apparently had problems with replicating my VAGCOM adapter, here is a "dry-run test". Here, the adapter is neither plugged into the PC nor the car.
A 12-volt power source, a voltmeter, and a set of measuring cables with crocodile clips are required.

The specified voltage values generally refer to ground potential.

Instead of crocodile clips, you can naturally solder normal wire pieces onto the connectors or hold them in place at the respective soldering points.
After checking, don't forget to remove the components

Preparation:
1. Connect pin 5 of the PC connector with the vehicle's ground wire.
2. Connect pin 4 of the PC connector with the vehicle-side 12V power line.

Tests:
3. Connect pin 7 of the PC connector to the vehicle's ground wire, and supply 12 volts from the vehicle side. Ensure that LED 3 is lit. The K- and L-lines should each be supplying 12 volts. The collector of T 1 shows almost 0 volts.

4. Provide 12V to Pin 3 of PC port. LED 3 must turn off, which means LED 2 must be lit. The K-Line should be close to 0V. Important: No voltage drop should be measured across R 6, if necessary VR 1, please configure accordingly!

5. As long as the K-line is connected to ground, LED 3 must always turn off, regardless of whether voltage is present on pin 3 of the PC connector.

6. Instead of ground, provide 12 volts on Pin 7 of the PC connector. LED 1 must light up, and LED 3 must turn off. The L-Line shows almost 0 volts.

Any other "logical behavior" of the adapter leads to functional errors.

Perhaps this can be used to identify functional errors.