# Problem with steering wheel controls and car radio



## Trapix (Feb 22, 2021)

Hello people !,

I have a 2011 Audi TT TFSI and I have a problem ... it turns out that I have installed an Android Wondefoo PX6 car radio and although it has CANBUS, it does not recognize the steering wheel controls and I cannot configure them.

After installing it, I have two loose cables (KEY1 and KEY2), which I thought it would not be necessary to connect when having Canbus, but according to the manufacturer's instructions, if it does not recognize me, I have to connect them to the steering wheel control control cables , which I have no idea how to locate ... is it necessary to disassemble the keypad?

Can someone help me to identify which are the steering wheel control cables, to which I have to connect the KEY1 and KEY2 cables, according to the attached diagram of the stock radio?

https://ibb.co/D848MN5

I don't think it is a CANBUS misconfiguration problem, as I understand it, for the Audi TT you have to select a simple Audi A3_A4, as indicated in the image.

A greeting and thanks in advance.


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## ADB (May 7, 2002)

I have a Xtrons PX5 unit in my TT. The chassis is a PF75ATTAR and I replaced the PX3 SoM board for a PX5.
Mine is configured exactly like yours for the CANBUS - AUDI_A3_A4(SIMPLE) and my steering wheel keys all work.
I'm sure you don't need the KEY1 & KEY2 cables connected if CANBUS is in use.
Have you tried any of the other CANBUS settings? I am sure there are others - BAGOO comes to mind?


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## Trapix (Feb 22, 2021)

Hello friend,

Thanks for your answer. Yes, I've also tried with the other two configurations and it has not worked either. The Chinese insists that I must detect the steering wheel cables and connect the keys. But I'm pretty lost with this.

Thanks for your help.


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## John949 (Apr 12, 2017)

Key1 and Key2 are for cars that use analogue voltage levels from the steering wheel controls. The MK2 steering wheel only sends CAN messages so There is nowhere you can connect these wires.

It is somewhat unfortunate that there is no standard for which CAN messages the steering wheel controls generate - it even varies between Audi models. A third party radio manufacturer therefore has to implement a large number possible mappings between the CAN messages from the car and the required radio function. Some manufacturers do a better job than others and some just plain don't work. You can keep trying different configurations but asking the manufacturer or finding someone else with this radio in a Mk2 would be quicker.

There is an expensive slightly silly solution and that is to use a third party CAN interface (e.g. Connects2). You could use this to interface with the CAN signals and get it to output analogue levels which you then can connect to your Key1, Key2 lines.


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## Trapix (Feb 22, 2021)

Hello John949,

I greatly appreciate your answer and all the information you have provided me to solve the problem. I have tried many configurations of this equipment and I can't get it to work with any. I will have to evaluate other alternatives because the manufacturer insists that I have to connect the key cables, so it does not offer me any solution. Thank you very much for your help.


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## Trapix (Feb 22, 2021)

Hi again friend,

This is the manufacturer's answer, he keeps insisting that I have to connect the Key cables for the steering wheel control to work:

"Before use steer wheel function , you have to connect all line right . then will will ok. you have to you connect key 1 and key2 line to your car steer wheel line, then steer wheel function will work good. every buyer have to do this step. hope you understanding 
key1 and key2 line is brown line. you can find out them easy and if your car have black line near steer wheel line too, please cut this black line too which near brown line, after connect them, all ok"

Can someone with a device of this style confirm if they have had to connect these cables to their Audi TT?

Thanks for the help.


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## John949 (Apr 12, 2017)

I think what the manufacturer is saying is that the head unit only works with analogue inputs for the steering wheel controls i.e. they have not implemented the CAN bus interface to the steering wheel controls.

It is feasible (but I have no idea if this is correct) that the steering wheel itself uses analogue voltages to send the state of the switches to the CCU, which then sends CAN messages to the head unit. Sort of like this.

Steering wheel -> analogue voltage -> CCU -> CAN message -> CAN compatible Head unit

They seem to be suggesting that you can tap into the wires between the steering wheel and the CCU like this:

Steering wheel -> analogue voltage -> Key 1 /Key 2 -> Analogue Head Unit

I'd want to be very sure this would work before I tried it and also that it wouldn't upset the CCU.

A much safer way to go would be:

Steering wheel -> analogue voltage -> CCU -> CAN message -> Connects 2 style interface -> Key 1 / Key 2 -> Analogue Head Unit

UPDATE Post from MT-V6 lower down suggests that steering wheel is connected to a local ECU via a LIN Bus interface so tapping into the steering wheel wiring will definitely not work.


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## Trapix (Feb 22, 2021)

Thanks again for the reply mate.

I'm still pretty lost. The manufacturer gave me the attached image. Should I connect directly to the steering wheel cables then or how should I do it?. Thanks.


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## jazzor (Feb 10, 2021)

I have reverse engineered several PX6 roms and I can assure you that the key 1 and key 2 is not required to be used.
The "simple" A3/A4/TT canbus is plenty capable of doing everything, including all the steering wheel buttons, and is used by many different android rom types (8257, teyes, PX5, PX6, etc etc). So either the seller gave you a bad rom or a bad canbus box.


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## Trapix (Feb 22, 2021)

Thank you very much also for your help jazzor!

May I have to choose some other setting when selecting Canbus type ?. The manufacturer ensures that I should leave the default values. Tried with VW&SKODA (simple and elevated) and Audi A_3_A5 (simple) and it did not work. The canbus was also changed for another in case it was defective and it does not solve anything either.

Thanks again!


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## jazzor (Feb 10, 2021)

Does other canbus functions work aside from the steering wheel controls? For example, if you turn the headlights on, the unit should reflect this by lowering the brightness and the soft buttons should turn on.
Does the door function work? Some roms (not all) allow displaying the door opening status. Does putting it to reverse switch the head unit to camera mode? These all require the canbus box -> head unit to function correctly.

If other canbus features work, then it could be the cable itself. The 16 pin simple canbus has pin outs for lights, ACC on/off, reverse, along with CAN H and CAN L. I would inspect the cable coming off each pin and see if that is going into the head unit correctly.

This is the simple canbus box pinout:


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## jazzor (Feb 10, 2021)

Also it might be worth posting a picture of your canbus box


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## MT-V6 (Jan 11, 2015)

Unfortunately I can't help with your problem, but just to add some info. The steering wheel controls have only 3 wires: power earth and LIN. I assume the steering wheel module converts the LIN into CANBUS where it can be picked up by the headunit

The LIN is also used to turn on the steering controls backlighting when the headlights are turned on, and also the gearbox paddle shifters if you have them

The controls on the right are actually a submodule, and will show in a VCDS scan as a submodule of the steering control module. The controls on the left are daisy chained into the ones on the right


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## John949 (Apr 12, 2017)

> The steering wheel controls have only 3 wires: power earth and LIN.


If LIN is a LIN Bus (Local Interconnect Network - a serial bus protocol) then connecting the KEY1 line to it will definitely not work and may well stop other things working.


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## tt21 (Mar 24, 2021)

@trapix hello, hope you can help.

I have purchased a wondefoo PX6, but cant seem to get it to fit my car, it gets stuck on the cage at the bottom, how did you get this to fit?

Thanks


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## Trapix (Feb 22, 2021)

Hello mate,

It didn't fit me either, I had to cut the box at the bottom with a saw about 5 cm horizontally.

Regarding the Canbus, despite attempts to help from colleagues (for whom I am very grateful), I have not been able to operate the steering wheel controls.

I hope it helps.

Regards.


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## tt21 (Mar 24, 2021)

Thanks @Trapix

That is helpful, as I dont have steering controls, so would like to make it fit.

Do you cut the unit or the cage in the dash?


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