How to read Steering Wheel Controls

[acittlau]

Hello everyone.

First post, but I've been reading quite a bit on the forum for the past couple of months. Tons of helpful information!

I have installed computer and touchscreen display in my veccy 2003 and want to control it using the steering wheel controls. But I have not been able to figure out how to read the resistance and/or voltage of these steering wheel controls.
The CDR2005 that was in the car has the sticker attached which shows pinouts.

What I've done is trying to check the resistance and voltage between the SWC pin and ground, 12v, aerial, ext.ill. But I can't see a change in resistance/voltage when pressing the buttons on any of these.

I'm quite sure I am not seeing something quite obvious here, but what? I would be really greatful for some input as I feel completely stuck.


Here is some background info for what I am trying to do http://www.mp3car.com/vbulletin/inpu...-controls.html

[stevedee3]

Bad news I'm afraid acittlau.

The steering wheel controls are not connected directly to the radio. The controls are connected to the CIM (steering column module). The CIM sends a digital signal over the low speed CAN bus to the display module. The display module then translates the message into a different digital format (I2C from memory) and that's what goes into the radio.

So you can't read voltages or resistance at the radio to determine which switches are pressed.

Sorry.

[acittlau]

Thanks for clearing that up stevedee3. That explains my poor results.

As I see it this leaves me two choices for making the buttons usable.

1. Hook into the cables that come from the buttons before they enter the CIM? If so, does anybody know if I can get to those cables without taking the steering wheel apart, and possibly the colors of the relevant cables?

2. Or I can buy one of the connect2 adapters which convert to e.g. sony stereos as I believe these will convert it back to varying resistance. But this of course feels like wasting money if I can get away with option 1

Andreas

[stevedee3]

1. Hook into the cables that come from the buttons before they enter the CIM? If so, does anybody know if I can get to those cables without taking the steering wheel apart, and possibly the colors of the relevant cables?

Not sure how accessible the wires are, but I can tell you the colours:
Pin 2 = Brown
Pin 3 = Blue/red
Pin 4 = Grey

The LEDs are connected between pins 2 and 4. The resistor-switch ladder is connected between pins 3 and 4.

2. Or I can buy one of the connect2 adapters which convert to e.g. sony stereos as I believe these will convert it back to varying resistance. But this of course feels like wasting money if I can get away with option 1

Some sort of CAN adapter would be neater, as you would only need to patch into one wire, and you could find this just about anywhere in the car. Don't know too much about what products are available for this option, but I'm sure others on this forum will have opinions...

[acittlau]

The LEDs are connected between pins 2 and 4. The resistor-switch ladder is connected between pins 3 and 4.

Ok, I'll check in the car tomorrow after I've searched a bit on how to remove the steering wheel, seem to remember seeing it somewhere on the forums here.

Some sort of CAN adapter would be neater, as you would only need to patch into one wire, and you could find this just about anywhere in the car. Don't know too much about what products are available for this option, but I'm sure others on this forum will have opinions...

Hmm, I was under the impression that only the newer steerings have CANBUS controlled SWC? I have one of the older with 3 buttons on each side.

Anywho, I'll post an update when I've had a good look in the car..


Andreas

[stevedee3]

Hmm, I was under the impression that only the newer steerings have CANBUS controlled SWC? I have one of the older with 3 buttons on each side.

I have the "older" system too. All steering wheel switches, bith old and new are connected via CAN. The difference is that the older radios (pre MY04.5?) didn't have a CAN interface. The older displays used to translate the steering wheel control signals for the radio. Newer displays don't have this functionality as the radio can understand CAN by itself. I hope this makes sense.

[florianu]

hello

I am also invloved in an issue like this but some different:
try to replace the old SWC 2003 with 2005. This, because I have changed ny CDR2005 and TID, with CD30 MP3 and GID.
Now the SWC are not functional because there are different signals, values, transmited between these 2 SWC in different MY.
The problem is that the old one has 4 wires coming out of the SWC module and the new one has only 3 wires.
Do enybody know what are the functions transmited by these wires and how I can use them?