2x2 diagnostic adapter without +12V

Hello everyone,
Could it be that there are 2x2 interfaces where the +12V line is not connected (and the diagnostic device must be supplied with +12V through other means) - for example, in 1Z engines from 1993/1994???

Hello, I'm not familiar with that. I believe it used to be that you had to plug a two-pin connector into the pump relay and connect a cable to the alternator or the battery's positive terminal (for gasoline engines).
Is the connector on the car not connected, or are you unable to measure 12 volts? Perhaps. Fuse blown?

I just took another measurement... without the ignition on, there's no voltage on any of the four terminals. With the ignition on, I'm getting just under 9 volts on the K line - there's nothing to measure on the black connector.

The fuse for the cigarette lighter is definitely okay - could it be something else (it's just too cold for me to pull them all out right now).

'In my Passat, I had removed the radio fuse (because my radio was connected directly to the battery), and even then, the VAG 1551 didn't work.' Maybe check that fuse sometime.

Best regards, WarLord.

It was fuse 21... now I have +12V, but my optocoupler interface (Ulf 3.0) still doesn't work - it seems to be normal for a 1Z from 03/94, though. Too bad!

Rainer's interface works perfectly with the 1Z. I had a 1Z model from 1994 and a 1Z model from 1996.

Best regards, WarLord.

...my optocoupler interface (Ulf 3.0) is still not working...

Does the software find the interface? The new VAG-COM versions no longer work with optocoupler interfaces.

Best regards, Frank L.

VAG-Com Shareware 3.11 found my opto-interface (also Ulf 3.0), but unfortunately, it was unable to establish communication with the control unit (ECU).

Maik's interface has (finally) fixed the communication problem.

Guys,

Take a look at the Ross-Tech website or the DRV websites. There are actually some instances with the 1Z models that 'don't want to have anything to do with VAG-COM.' This isn't necessarily due to the adapter, provided it's properly constructed.

I find it hard to believe what Tino is writing about the ULF 3.x not working. It should be able to perform diagnostics. Maybe it was a problem with the setup? While Maik's adapter and the ULF 3.x differ significantly in terms of technology, they are quite similar in their functionality.

By the way, who's saying that VAG-COM doesn't support opto-adapters in the newer versions? VAG-COM doesn't care what's connected to the RS232 interface, as long as the voltage levels and signal timings are correct! Again, please use the search function. We've discussed the advantages and disadvantages of the different adapter versions to exhaustion, dissected their functionalities in minute detail, and discussed solutions and tricks for potential communication issues!

I wouldn't rule out the possibility that I made a mistake somewhere with Ulf's adapter. The adapter was recognized by VAG-Com, but it didn't establish any communication.

I also read somewhere on an official website that the new version supposedly won't support optocouplers, but I agree with you: as long as the voltage levels are correct, it shouldn't matter to VAG-Com.