MFD G: TV Tuner Emulation Guide

CAN-Diagnose · Translated on 19-08-2026, 19:18.

Hello there!

It's about the topic of "TV tuner emulation" on the VW radio navigation system MFD (version G!). The device has the part number 3B0035191G.
The goal of the emulator is to evaluate the key presses on the MFD using a microcontroller.

I connected my CAN interface directly to the MFD. Unfortunately, I don't have a TMC box or a TV tuner for sniffing data (they are a bit too expensive...). However, it seems that the communication is working even without them(?).

The following IDs are known:

0x464: MFD to tuner.
0x264: Tuner on MFD.

and as a keep-alive packet, I send it cyclically to the MFD:

Code:

Dir Time Type ID Len Message
-TX- 695 Standard 0x264 2 0xA1 0x01

Found here in the forum: http://www.canhack.de/en/viewtopic.php?t=914.

When the Keep-Alive packet is sent, the entry in the source selection of the Multifunction Display (MFD) changes from "AUX (V/A)" to "TV/VIDEO". This indicates that the MFD seems to be recognizing some kind of tuner. If the next Keep-Alive packet is delayed for too long, the entry reverts back to "AUX (V/A)".

Now the problem:
In "TV/VIDEO" mode, no key states are transmitted.

Code:

Dir Time Type ID Len Message
-RX- 115 Standard 0x464 3 0xE0 0x01 0x00 // Timeout-Frame? Hier wechselt die Anzeige zurück.
-TX- 979 Standard 0x264 2 0xA1 0x01 // Keep-Alive Tuner -> MFD (im 1s-Takt)
-RX- 1095 Standard 0x464 2 0xA3 0x00 // Keep-Alive MFD -> Tuner?
-RX- 1197 Standard 0x464 2 0xA3 0x00
-RX- 1298 Standard 0x464 2 0xA3 0x00
-RX- 1399 Standard 0x464 2 0xA3 0x00
-RX- 1501 Standard 0x464 2 0xA3 0x00
-RX- 1601 Standard 0x464 2 0xA3 0x00
-RX- 1703 Standard 0x464 2 0xA3 0x00
-RX- 1805 Standard 0x464 2 0xA3 0x00
-RX- 1906 Standard 0x464 2 0xA3 0x00
-TX- 1930 Standard 0x264 2 0xA1 0x01
-TX- 2881 Standard 0x264 2 0xA1 0x01
-TX- 3832 Standard 0x264 2 0xA1 0x01
-TX- 4783 Standard 0x264 2 0xA1 0x01
-TX- 5734 Standard 0x264 2 0xA1 0x01
-RX- 6097 Standard 0x464 2 0xA3 0x00
-RX- 6199 Standard 0x464 2 0xA3 0x00
-RX- 6300 Standard 0x464 2 0xA3 0x00
...

Unfortunately, I haven't found anything helpful on this topic through Google or forum searches.

Has anyone managed to get this working with a MFD version G, or does anyone have a MFD version G with a TV tuner that they would be willing to create a log from?
Since the TV tuner, according to the wiring diagram, is also connected to the navigation system's CAN bus (or MCNet), I suspect that the buttons are not being routed to the comfort CAN bus.

"I've also noticed that the MFD completely ignores the value in byte 2 of the Keep-Alive frame from the tuner; the result remains the same."

I've attached a recording of the MFD startup sequence (the device is on the table, so the responses from the MFA, etc., are missing).

Thank you in advance!

CAN-Diagnose · Translated on 19-08-2026, 19:23.

Hello,
I've only been active in this forum for a few days, and I just happened to come across your thread.
Here's a brief introduction about me: My name is Thomas, and I'm from Mülheim/Ruhr, postal code 45472.

Right now, I'm tinkering with a Mercedes Comand 2.0 DX and an old Becker TV tuner on my desk.
The goal is to emulate the tuner.

I recorded the startup sequence and also figured out what is transmitted on the local CAN bus, which in Mercedes-Benz only connects to the TV tuner, when you press buttons or turn the knob on the device itself.
Since the MFD is obviously very similar to the Comand system, there are likely to be parallels between them.

"Keep alive" works the same way for me, even with "264 A0 01 00", which is what I've extracted from the data stream. I can use this to simulate a tuner for the command.

Here's an example of what is sent from the control unit to the tuner when you turn the right rotary knob:
clockwise:
464 10(...1F) 35 01 01 00
"das (...1F)" means that with each pause, the counter increments from 10H to 1FH and then restarts at 10H.
to the left:
464 10(...1F) 35 02 01 00