CAN Interface Test: No CAN Signal?

Hello,

When I click the "Test" button on my HEX CAN interface, I get the following results on my Polo (manufactured in 2004), among other things:
K1 = OK, K2 = OK - obwohl der Polo keine 2. K-Line has...
CAN not ready (or something similar) - even though the Polo has the CAN pins of the OBD interface connected.

Where is the logic behind this ?

However, the Polo does not have a direct diagnostic CAN bus.
You will only receive the 'O.k' message on vehicles equipped with a CAN gateway, such as the Audi A3 8P, A6 4F, A8 4E, Volkswagen Golf 5, and similar models from Skoda and Seat, like the new Altea or Octavia 2.

Please note that this applies to all users for whom the new 'Auto-detect' option in the Auto-scan menu is working correctly.

I think this is correct so far – otherwise, someone will definitely correct me.

You only need CAN to access the braking system. My KKL interface didn't work with it.

The connection test checks the data bus; it does not explicitly check for a gateway (which is not installed in models like the A4 8EC/8ED/B7, but these models still use CAN diagnostics for the engine control unit).

bastion wrote:

You only need CAN to access the braking system.

It didn't work with my KKL interface. }

No, the Polo 9N is 100% K1, not K2, and it doesn't use CAN bus technology.

Why didn't it show up in the braking system diagnostics then? It only illuminated a symbol on the instrument cluster, and nothing happened when I checked with VAG-Com.

What diagnostic interface are you using, and which version of VAG-COM?

If the light briefly turns on, it means that the control unit has at least detected that a connection is being established.

Sebastian@OpenOBD wrote:

The connection test checks the data bus; it does not explicitly check for a gateway (which is not installed in models like the A4 8EC/8ED/B7, but still allows diagnostics via the CAN drivetrain). No, the Polo 9N is 100% K1, not K2, and has no CAN bus functionality.

Hi Sebastian,

nothing CAN?
In the SLP (likely referring to a specific vehicle model or system), two wires explicitly run from the OBD interface to J 533 (which is the diagnostic interface for the data bus), and these are present as twisted pairs in my car, as they should be.
I'm just wondering why I'm getting the "CAN not ready" message...

Sebastian@OpenOBD wrote:

What diagnostic interface are you using and which version of VAG-COM? If the light turns on briefly, then the control unit has at least detected that a connection is being established.

It's a KKL interface from PCI Vetter and VAGcom 303.11 shareware. It might be due to the outdated software.

ulf wrote:

In the SLP (Steering Linkage Positioner), there are explicitly two wires running from the OBD interface to J 533 (= diagnostic interface for the data bus), and these are also present in my car as a twisted pair, as they should be. I'm just wondering why I'm getting the "CAN not ready" message.

These are remnants from the development process; these CAN lines are either dead or non-existent in reality (even though they may appear in the SLP file). It's possible to "revive" them with a few tricks, but it doesn't provide much benefit for diagnostics.

bastion wrote:

It's a KKL interface from PCI Vetter and VAGcom 303.11 shareware. It might be due to the old software.

Okay, then take another look at Vetter. However, the interface may not be technically comparable to a HEX or KEY system, so the source of the error could also lie there.

Hello, I've had similar experiences as well.
The CAN bus system is present throughout the entire vehicle, but there is absolutely no CAN bus in the Seat Leon 1M with an ASV engine.

The reason for this is the modular design: in the Audi A3, the PQ34 platform uses a CAN bus system, while in the Seat, the electrical architecture is more similar to a Golf 3 than a Golf 4.
However, the wiring harness is still almost identical. Therefore, only one wiring harness needs to be manufactured.
This experience has cost me several weeks of work (unfortunately, much of it was unnecessary).

Since there's likely a Polo with features like air conditioning, ESP, and other extras, and Ulf isn't using any of those features, the necessary wiring is already in place but not being utilized.

Best regards, Jochen.

P.S. Be glad that you don't have a CAN bus, because then there can be no unexplained communication problems .

bastion wrote:

It's a KKL interface from PCI Vetter and VAGcom 303.11 shareware. It might be due to the old software.

Bingo!
According to Uwe Ross, for the 9N with ESP, the price definitely starts at 409 and goes up from there. I had the same problem – the software was too old.

Hello, I have also had the same experiences in the meantime.
The CAN bus system is present throughout the entire vehicle, but there is absolutely no CAN bus in the Seat Leon 1M with an ASV engine.

The reason for this is the modular design: in the Audi A3, the PQ34 platform uses a CAN bus system, while in the Seat, the electrical architecture is more similar to a Golf 3 than a Golf 4.
However, the wiring harness is still almost identical. Therefore, only one wiring harness needs to be manufactured.
This experience has cost me several weeks of work (unfortunately, much of it was unnecessary).

Since there's likely a Polo with features like air conditioning and ESP, and Ulf isn't using those features, the necessary wiring is already in place but not being utilized.

Best regards, Jochen.

P.S. Be glad you don't have a CAN bus, then there can be no unexplained communication problems .

'I don't quite understand your post. In both the 1M and the 1J, diagnostics are exclusively done via the K-Line... The Leon has a motor-CAN and a comfort-CAN, just like the Golf IV... Where do you see the problem there? And of course, data is exchanged! I only connected the comfort-CAN from the comfort control unit to the instrument cluster (KI) in order to have the door symbols displayed on the Highline MFA.'

A Volkswagen Golf 3 did not have any CAN (Controller Area Network) functionality at all.

So, who is always saying that the SEAT Leon 1M has a CAN bus?

I have checked the physical connections for CAN activity alone: there is no reference voltage level, no termination resistor, and nothing else that the CANalyzer interprets as CAN activity!
Besides the twisted wiring throughout the vehicle that isn't being used.
Several workshops have confirmed this to me. The electrical system of the Leon is actually quite different from what many people (including myself) might think.
Please note: This is for a Leon 1m with ASV!
For vehicles with an automatic transmission or electric powertrain (EV), this is different for the engine. However, it's the same in terms of comfort features.

Apparently, the same thing is happening with Ulf's Polo. That's why I started this thread.
The diagnosis of the Leon is performed exclusively via the K-line, correct?
Just like the Volkswagen Golf 3, it also doesn't have a CAN bus system!

There's no problem as long as you don't need to read values from the CAN bus.

Best regards, Jochen.

Okay, so if I disconnect those two CAN bus lines from the control unit or the speedometer, or whatever, then nothing works anymore.

The speed signal and other data are all transmitted via CAN bus, not directly through a 12V signal or tachometer shaft.

I recently installed an engine from a VW Passat 3BG into a Seat Leon 16V myself, and it works just the same.

Perhaps you should share information about production/model years with each other.

Okay, so the 1M has had '920' AI models since the SOP (Standard Operating Procedure).