OBD2 adapter

Hello,

I'm getting really frustrated trying to build my own OBD2 interface.

Now I've built Jeff N.'s circuit for the 2nd time (with new components), and the thing isn't working again .

I really don't know what I'm doing wrong. It's not that difficult, actually.
I used a breadboard for the experiment. I left all the resistors as they were, and the labels for the capacitors, transistors, and diodes are correct. I had to use CNY17-4 optocouplers because I couldn't find the ones specified in the instructions anywhere.

Okay, I always get adapter status 3 (not found) in VAG-Com. I also know that the device needs to be connected to the car in order for the adapter to be found. I'm about to lose it...

Has anyone else experienced similar problems during assembly?
I'm also not sure where to start looking... Could someone perhaps give me some tips on what I could check with a multimeter, for example (some resistors or something like that)? I have reviewed the individual resistors, the circuit diagram, and the connections multiple times, but I have not been able to find any errors.

In VCDS (formerly VAG-COM), there's a function called 'LEDs.' Where should the LEDs be soldered in for testing purposes?

Thank you in advance for your patience and any helpful tips you may have.

Best regards,
David.

Search function, keyword 'diagnosis adapter'

If I remember correctly, all of your questions should already have been answered there.
Here's another tip: double-check that the wires of the serial connector are connected correctly. I've accidentally soldered the wires in reverse order on the connector more than once.

Best regards, Rainer.

Of course, I used the search function first, that's obvious.

But I haven't found anything about the adapter not being recognized (unfortunately). , or what one could check.

It is stated how he is identified. In addition, Rudi still had to modify a resistor.
Did you read it?
Are you absolutely sure that the RS232 connectors and the optocouplers were not accidentally wired in reverse?

Best regards, Rainer.

I've already tried everything, and I've tested it on different computers, but I always get the same result. What would be helpful is information like, 'There is a resistor of xxx ohms connected between pin 2 and pin 3.'

Just so I can grab my multimeter and check those values for verification.

Here's a picture of my RS232 connector from the front (the one I plug into the PC). I soldered the cables directly to the board, without using any adapters.

Please provide the text you would like me to translate from German to English.
X X X X O /
\ O O X O /

Based on your ASCII image, the pinout matches.

[url][/url] TIA457, Male (connector)

According to the circuit diagram, pins 2 and 3 (Rx, Tx), pin 4 (DTR), pin 5 (GND), and pin 7 (RTS) are connected to the PC.
Measuring resistance between, for example, pin 2 and 3, or anything else, is actually quite pointless. You might be able to detect a short circuit, but that's about it. Just strictly follow the circuit diagram.
Are the individual wires at the connector reversed?

Best regards, Rainer.http://www.connectworld.net/rs232.html{MARKER}

Thank you for your efforts so far!

But: my failed picture actually shows a female. The connector (the COM port on the PC is male) is facing forward, and pin 1 is on the right (thanks for the link), and that pin is not connected.

I also had a reverse-polarity plug custom-made once for testing (because I was worried I might have wired something incorrectly...).

*LOL*

Too late... You're right. I just checked a connector, and your pin configuration is correct.

Hi.
I built the interface today as well, using the CNY14-4, but it's not working. Polo with a 1.9L 3F engine and K-Jetronic fuel injection.
Okay, I can explain what the interface does.

"I've connected the power supply, and when I connect a test lamp from the positive terminal to ground (K), the lamp starts blinking irregularly. It also starts blinking on the L-line, but with a significantly lower voltage."
Is that correct so far?
When I run this LED test, it starts blinking on the K-line, but nothing happens on the L-line.

1993 Polo? You should also have an L-line there, shouldn't you...?

Do you use VAG-COM? Is the adapter recognized on your system? (under 'options')

I bought one from eBay, but it only has a K-line connection. It's recognized, but when I run the OBD2 test, the program tells me that my car is not OBD2 compatible. I'm blaming it on the fact that the L-line isn't available!

Okay, the L-cable thing is no problem. I have an Ibiza here that needs that too.

and the two interfaces that I created myself are also working perfectly. They are exactly as specified in the circuit diagram. Where is the problem?
Have you really connected all the cables and connections?
BC-546 transistors, CNY17-3 or ILQ5 optocouplers, 1N4007 diodes. All resistors according to the circuit diagram.

In Germany, a car must be OBD-2 compliant starting from the year 2000, while diesel vehicles must be OBD-2 compliant starting from the year 2003.

CU Gremlin.

Good evening.
VAG com reports COM port status: OK; Adapter status: 0 (Ready); Fast sync compatible: NO (makes no difference whether with or without the vehicle).
Potential fluctuations occur on the L and K lines when I try to access a control unit.
I think the problem lies in the receiving end.

I adjusted the starting bid to 2600 again today, but it didn't help.
Then I increased the R7 resistance to 10k, but that didn't help either.

I suspect the CNY17-4 is faulty. I'm using a BC-546A as a transistor, and some silicon diodes from an electronics kit.

Has anyone ever used this interface with CNY17-4 sensors?

incidental
I am 99% sure that I have a yellow/white cable in my car that is a K-line.
The 45 and 55 horsepower Polos had the L-line until the end of the 1992 model year, but otherwise, there was no L-line in the Polo. Also, can you read diagnostic data blocks with the L-line?

Hello.
Here's the situation I'm facing:
While it works perfectly on my laptop, it doesn't work on any of my desktop computers.
Com Port Status: OK, Adapter not found.
Same operating system as on the laptop: Windows XP and Windows 98SE.
Maybe this will help, or perhaps someone can give me a tip.
I've tried all possible options regarding the COM ports and the configuration of the COM software.
Best regards, Olli.

Hello Oliver,

Have you already checked the basic functionality of the COM ports on your desktop computers? For example, by using a modem, a loopback cable, or a null modem cable to connect one port to another? No yellow exclamation marks next to the ports in the Windows Device Manager?
Are the ports also enabled in the BIOS?

Best regards, Rainer.

Finally, someone who has the same problem .

'I also always get the 'adapter not found' error, even though the COM port is working.'

Could someone please post what requirements are necessary for the adapter to be detected?
There was already a discussion about this in the forum, but no solution was found (a 150k resistor between pins 2 and 4 is not sufficient).

Yes, the COM port settings are correct, and everything is also enabled in the BIOS.
The ports are also working (including the modem).
One possibility is that my laptop only has one COM port (COM1).
The Deskrechner, but version 2.
I also tried disabling each COM port one by one, or using an adapter to switch to a different COM port, but without any success.
Similarly, swapping the COM connectors on the motherboard yielded no results.
PS: The COM port configuration in the Control Panel on the desktop PC is the same as on the laptop.
Similarly, an attempt to reconfigure the software using VAG Com to a different port was also unsuccessful.
I'm really at a loss as to what that could be.
I actually intended to use my workshop PC for the data logging and only use the LAP for recording driving sessions.
It would be more comfortable for me.
Well, maybe we can find a solution together after all.