You will need
Check the adapter without connect to the car. Since the line after the adapter is the one you can send a signal to the port and then execute it read in the "Echo". Next, connect the adapter to the PC, use a program designed for the diagnosis of computer – Check It 3.0.
Enable diagnostics com port in the Windows, observe the reception-transmission of symbols. If everything is OK happens, we can indirectly judge about the operation of the circuit. Examine with an oscilloscope the signals K-Line, and RxD. The magnitude of the signals on the SOM should be from +12V to 0V. On K-Line, the value should be the same. Similarly to do the test adapter K-Line using the diagnostic tool ICD.
Use a simple electrical tester to test the adapter the K-Line. Make sure that all the circuit elements of the adapter are installed correctly, apply +12V verify output on the MAX232 the presence of +5V. If not, check your installation 142ЕН5.
Check the operation of the converters MAX232, ie you should be set to +10V 2 output. Post on the receiver input RS232 -10V, to do this, connect the terminals 13 and 6 МАХ232, check the signal. Delete the pairing. Connect the port RS-232 adapter to your computer, connect with k-line, run setup with the controller. Check the settings of the com port, the value of the resistor in the load, as well as the quality of the communication line.
Check the operation of the adapter, this will connect it to the computer, turn off the power to it. Open the main menu, select "Programs" – "Accessories" – "Communication" – "HyperTerminal". Go to menu "File", select "Properties", then "Connect via", select the com port that matches the host and click "OK". Next, complete a set of any characters from the keyboard. If they are visible on the screen, the adapter is functioning properly.