KEY-USB Interface Failure: Short to Ground?

Help!

I wanted to read the error codes from a Golf IV TDI, but it didn't find the control unit.
I then tested the communication interface in the settings. The results were as follows:

Communication interface: Okay.
Diagnosis system: found.
Type: Ross-Tech Key-USB
Status: questionable.
K1: Short circuit to ground.
K2: Short circuit to ground (sometimes works after wiggling the plug).
CAN: Not available.

First, I thought it might be a problem with the car itself. Then, I started trying it out on an Octavia I.
Unfortunately, the same problem exists here as well.
Three days ago, everything was still working. (Sharan)
Has anyone of you ever experienced a similar problem?

Thank you.

Hello Tobi,

I had a similar problem a few days ago.
For me, there was only a short circuit to ground on input K1.
However, when I removed the lower dashboard panel, I found a cable that was pinched between the panel and its bracket.
There, the insulation was almost completely gone, and there was a short circuit to ground.

I'm not saying that the same issue applies to the two cars you were trying to fix.
But it's also possible that your cable or connector is faulty. If a pin has come loose and is now touching the other contacts, that could be the cause of the short circuit.
Ask Rainer (if the equipment belongs to him) if he can comment on it.

Thank you for the response.

Is Rainer the manager of the online shop, right?
Is he also active in this forum, or should I contact him through the shop?

Is it possible to remove the pins, or should I send the interface back for repair instead?

It would be a real shame if that good interface was ruined. It has always worked perfectly well so far.

I took some measurements. The resistance from the ground pin to the other pins is 900 ohms in one case and 700 ohms in two other cases. A direct short circuit cannot be measured.

Of course, I have no idea what values I should actually have.

Can someone please double-check the measurements?

Thank you.

Hello Tobi,

Rainer is the manager of the shop and also the head of the forum.
So, it's all in his hands.

Why don't you send him a private message if you have that item from him?
Otherwise, he will understandably reject the support.
Perhaps he can help you with measurements or a replacement interface.

I also believe that the connections behave differently when they are plugged into the diagnostic interface.
Perhaps there's also some clever technology involved that hasn't been activated yet.

Hello Tobi,

Quote:

Is he also active in this forum, or should I contact him through the shop?

For support questions, the contact form on the website is the best option. While I regularly browse the forum, I unfortunately can't follow every topic due to time constraints.

Please provide your invoice number (via the contact form) if there is no burn mark on the K-Line transceiver, which may have occurred due to the use of a low-quality 2x2 adapter (it is possible to connect the plugs in the wrong orientation in the car!). Otherwise, the warranty applies.

Best regards, Rainer.

Ah, there's the boss.

Hello Rainer,

I did have an adapter connected to it before, but it was also from your shop.
With the adapter, the interface still worked perfectly. If there had been any reversed polarity, I would have encountered problems there, right?
Then, a Golf III and a Sharan arrived, and there were no problems with those either.
It was the Golf IV that first started giving problems.

Could a wiring error in the car pose a risk to the interface?
There should be a safety mechanism built into the device to prevent damage to the interface.
Nobody knows who messed with the wiring before.

Best regards.
Tobi.

Tobi76 wrote:

... It was the Golf IV that first started giving problems. ... Nobody knows who messed with the wiring before.

Has a different car radio been installed in the Golf IV? So, is it not the original radio that is installed?

Hello Bertil,

I didn't pay attention to that. But after a phone call, I was able to find out that it's an original radio and that no other radio had been installed before.
A CD changer was retrofitted at some point.

Best regards.
Tobi.

Tobi76 wrote:

... that it is the original radio and that no other radio has ever been installed.

Okay... then my objection is not valid.

But let's talk about the future.
Starting with generation G4, the car radio is connected to the diagnostic bus. If an aftermarket radio is installed without the appropriate adapter, it can cause voltage on the diagnostic bus. This can potentially damage not only the diagnostic computer, but also some control units. Although the error is rare, I have seen several cases of it.