Problem with Ulf's OBD adapter

Hello,

I just replicated the adapter from Ulf .

The adapter works in the test, and I'm getting a baud rate of 57600 during the loop test, so I assume the connection on the PC side is working.

After that, I measured between the mass and the K-Line (with the K-Line disabled), and I get 12V http://www.dieselschrauber.de/Adapter%20trimmbar.png).

The same applies to the L-Line.

'Now, when I turn on the individual channels, I can adjust the voltage from approximately 0.3V to 12V. However, I eventually encounter a huge jump in voltage (perhaps a different potentiometer would help?).'

It would be great if someone could help me.

Thank you & Best regards.
Benny.

Hi,

Okay, I can't find any errors in your descriptions at the moment.

K- and L-lines in idle state -> 12V relative to ground.

activated -> approximately 0 volts.

What's your problem?

Are you unable to connect to the vehicle?
-> First, check everything from the article.

Hm, the documentation for the Oktest says the following:



2. Static baseline adjustment of the adapter (measurement device required).
Connect the adapter as described above. Re-establish the connection with the COM port being used in the adapter test -> the PC switches the RTS signal from the negative to the positive voltage range; for the proper functioning of adapters that are powered by the PC, a minimum of 4 to 5 volts is required.

Connect a measuring device between the L-line and the vehicle-side adapter supply (!). There must be no measurable voltage present.

I'll just try it out tonight when I have some time.

'Thank you anyway for the quick response!'

The cable works, but isn't the text in the TestOK software then incorrectly phrased? :-]

Regards,
Benny.

BennY- wrote:

The cable works, but isn't the text from the TestOK software then incorrectly phrased? :-\

It could be (at least, it's open to interpretation). I will check it again.

Hello!

I hope Ulf can help me – I just received this yesterday.
I recreated the adapter, but I have to admit that I'm not really...
I have experience with electronics, but I'm always ready to learn something new.
to try.

Okay, the adapter is mostly finished. I followed the instructions as described.
I described a function test, and now I need to proceed with it.
First time installing it - I had LED 3 installed upside down.

Okay, so I followed this pattern:

Preparation:

* Connect pin 5 of the PC connector (GND) to the vehicle's ground connection.
* Connect pin 4 of the PC connector (DTR) to the vehicle's 12-volt power line.
* Set all trimmers to their maximum setting.

Tests (measure voltages with respect to ground; the voltages to be applied should also be understood as being with respect to ground!).

* Connect pins 3 and 7 of the PC connector (TXD and RTS) to the vehicle's ground rail and supply 12 volts from the vehicle side. Ensure that the K-line and L-line each carry 12 volts. The collector of transistor T3 must not have any voltage. LEDs 1 through 3 are not lit.
* Connect 12 volts to pin 7 of the PC connector instead of ground. LED 1 and 3 must be illuminated; this corresponds to a specific state of the LED test within the VAG-COM menu.
Then, connect pin 7 to ground again.
* Apply 12 volts to pin 3 of the PC connector (TXD). LED 2 should light up. The collector of transistor T3 should be at 12 volts. This corresponds to the data flow from the PC to the car.
* Connect pin 3 of the PC connector (TXD) and the K-line to ground. LED 3 should light up as long as the K-line is connected to ground. This corresponds to the data flow from the car to the PC.

So far, everything is working fine except for the last point, when I connect the K-line to ground.
connects, LED 3 does not light up
I've made another mistake here; I installed OK3 upside down as well. I hope...
'...this prevented anything from breaking... I replaced the OK3 with a new one, which...'
now also properly installed

The shareware version of VAG-COM 311.x also cannot find the adapter, even though...
The LED test is working; LEDs 1-3 light up briefly simultaneously and then flicker randomly.
mixed up 1-2-3, etc., with LED 3 being slightly illuminated.
If VAG-COM is searching for the adapter, LED 3 will blink, but the adapter will not be found.

The TEST OK program turns on LED 1 and 2 as intended, specifically pins K and L.
The lines will either be at the specified voltage or have the described 12V.
The LOOP test is not working, and the PULSE-Line is causing the computer to crash.

And LED 4 is always on - because there is voltage there .

Does anyone have any ideas where I might be finding an error? Unfortunately, I'm more of a beginner.
someone who knows about it.

Sure, no problem! Here's the translation:

'Thank you in advance!!'

TheBeer wrote:

Does anyone have an idea where I might be finding an error? Unfortunately, I'm more of a novice than someone who is familiar with this.

As stated in the technical article: a quick remote diagnosis is practically impossible.

T3, correct type, in good condition, and properly installed?
Was bedeutet "VR 3 nicht auf Null gedreht?"
R 10, is the correct value?
No solder bridges or incorrect wiring around OK 3?

etc. etc.

-> It's best to really have a qualified electrician take a look (don't take it personally ).

Hello!

So, the adapter is now
It was the VR 3 that wasn't fully activated, as I'm referring to something else here.
The design had to be adapted, but in this case, the value wasn't as high.
to adjust it to the way it should be.

Thank you for the tips!