Passat 3BG MFL: Parts & Repair Guide 2004

Hello,

I have a Passat 3BG manufactured in May 2004 and I bought a Zenec 2041d, which supports steering wheel controls. I also got a programmable interface from Connects2 (with DIP switches... so not really programmable). However, with this interface, only the volume up/down functions work; track +/- doesn't work.

I inquired about it, and apparently there's no interface for that. As an electrician, I can't understand why you can access the protocol or data set for volume control but not for track selection (i.e., +/-). While searching online, I came across this forum.

'In principle, it should be possible to create such an interface yourself. Reading the CAN bus and determining which data sets are sent with Track + - should be feasible. However, I'm completely new to this area; I have some experience with PLCs and EIB, but I don't know anything about CAN.'

The interfaces that are being sold are called CAN/Stalk interfaces, so I assume that 'Stalk' is the protocol that the radio understands, or perhaps an analog signal?


Can you help me with this, or should I just give up?

Information about what I need.

How do I read the CAN data? (I should be able to find that information in the forum...)
Is there a CAN/LIN interface that can be programmed?

Thank you.

blacknois wrote:

I have a Passat 3BG manufactured in 05/2004, and I bought a Zenec 2041d with stalk support. I got a programmable interface from Connects2 (with DIP switches... so not really programmable), but it only allows me to control the volume; track +/- doesn't work.

More details! I don't want to have to Google that myself - what kind of interface exactly?
Womit willst du bedienen? Steering wheel buttons?
Is the Zenec unit designed for the Passat/Volkswagen?

Quote:

I inquired about it, and apparently there is no interface for that. As an electrician, I can't understand why you can access the protocol or data set for volume control but not for track +/-. While searching on Google, I came across this forum.

Perhaps it's a niche product; in principle, you are absolutely right.

Quote:

In principle, it should be possible to create such an interface yourself. Reading the CAN bus and determining which data sets are sent with Track + - should be feasible. However, since I'm completely new to this area, I have some experience with PLCs and EIB, but I don't know anything about CAN. The interfaces that are being sold are called CAN/Stalk interfaces, so I assume that "Stalk" is the protocol that the radio understands, or perhaps an analog signal.

No. "Stalk" is the English word for "steering column lever."

Quote:

How do I read the CAN bus data? (I should be able to find that information in the forum...)

There is (was?) a DIY interface available on this forum.
I personally use one from Peak.
[url]http://www.peak-system.com/Produktdetails.49+M5f1e2159727.0.html?&tx_commerce_pi1[catUid]=6&tx_commerce_pi1[showUid]=16[/url]

From Connect2, the CTS Uni.
I want to control the radio using the buttons on the steering wheel.

The Zenec is specifically designed for my car.
http://www.zenec.com/de/produkte/ego/volkswagen-seat/ze-nc2041d/

How is the signal then transmitted from the interface to the radio? Is it an analog signal?

Okay, reading the data shouldn't be a problem, but how do I build something that converts the signal for the radio?

Thank you.

I just spoke with Dietz, and their interface works!
I've placed an order, let's see what happens...

Hello.

The Zenec interface can natively and correctly implement MFL commands.
However, while the MFL commands always appear with the same identifier on the CAN bus, they have different byte lengths.

Your Passat, for example, sends MFL messages that are only 1 byte long, but the Zenec interface expects 4 bytes.

Convert the 1-byte message into a 4-byte message (simply fill the last 3 bytes with 0x00 each), and that should work.

That's also the reason why many people have to install a new gateway in their old car to operate a brand-new radio.

Regards.

Hi there,

Quote:

Your Passat, for example, sends the MFL messages only with a length of 1 byte, but the interface from Zenec expects 4 bytes. Convert the 1-byte message into a 4-byte message (simply fill the last 3 bytes with 0x00 each), and that should work...

I think you might be asking too much of the surgeon.

Quote:

That is also the reason why many people have to install a new gateway in order to operate a brand-new radio in their old car.

It sounds like you have the entire CAN infotainment matrix laid out in front of you.
Want to share some secrets with the rest of the world that doesn't know?


Best regards,
Ingo

Hello.

Yes, I have this 'Matrix,' which is the message catalog, right here.
I acquired this knowledge myself through approximately 10 to 12,000 hours of work, and now I know every detail, at least within the comfort and infotainment area.

The process at MFL is as follows:

The steering column control unit periodically checks the state of the buttons on the multifunction lever (MFL) every few milliseconds via the LIN bus.
The result is now transmitted from this control unit to either the vehicle's body control module (via LIN bus - e.g., Golf 4, T5 2003-2009, etc.) OR to the gateway (CAN comfort).
If the message is sent to the gateway via CAN, it always has the same format – it's a single byte long.
The CAN gateway is now handling the communication for the infotainment CAN bus.
Depending on the installed gateway version, this results in a message that is either 2, 3, 4, or 6 bytes long.
Except for the first byte (which contains information about the key state), the remaining bytes are filled with 0x00.
The radio doesn't just blindly read the value of Byte1; it also expects a specific message length, depending on the device's manufacturing year or part number.

The 'malfunction' of the MFL (presumably a specific function or feature) after a software update of the radio (e.g., RNS 510) is therefore intentionally designed by the company, as there is no further reason to artificially expand a message by up to 5 bytes, which cannot be utilized anyway.

Perhaps some of you are familiar with the phenomenon where the car battery discharges after a software update for the RNS 510 system.
Again, this was only due to the fact that the length of the status message from the RNS 510 had been changed (from 6 to 8 bytes), but the gateway was only passing through 6 bytes.
However, the last byte contains information for all other participants on the bus: 'I would like to go to sleep now.'
So, after the car was turned off, the CAN bus remained active the entire time. After installing a new gateway, the error disappeared.

I would like to reiterate one point: When examining CAN messages, don't look at them in hexadecimal format, but rather in binary format.
The value, for example, 0xA0, is meaningless...
The bit configuration at the binary level, such as '10100000', reveals more information, especially when the value changes suddenly.
Only in this way can you assign each individual 'switch' to a function...

Whoever may be equipped with a 'megabrain' and can represent hexadecimal values in binary format in real-time, can do without this . I, like many others here, cannot.

Hello.

The bit configuration at the binary level, such as '10100000', reveals more information, especially when the value changes suddenly.
Only in this way can you assign each individual 'switch' to a function...

Whoever may be equipped with a 'megabrain' and can represent hexadecimal values in binary format in real-time, can do without this . I, like many others here, cannot.


You don't need a genius brain for that. I personally find hexadecimal (HEX) much more informative, and in my opinion, changes are visible much faster. As soon as I see a HEX number, the binary pattern is already in my mind, and I can also quickly calculate the decimal value mentally.

Hello.
Ultimately, it's up to each individual to decide.
I can't do that, and it doesn't even need a decimal value anyway...
I can't easily determine, just by looking at the value changing from 0xA0 to 0xEB, which specific bit(s) have changed.

I can also manage to get from 0xA0 to 0xA1 .