Half-Can Steering Wheel Button Wiring

**Gayno** · 7th December 2010, 14:55

Hey guys,

I've got a pre-face with the half can buttons on the steering wheel.

Does this mean the buttons interface directly to the stereo?

If so do you know which wires they are at the back of the stereo?

Have got a car button controller to interface the buttons with my upcoming CarPC project and need to know which to connect to.

Many thanks

Adam

**kenp** · 7th December 2010, 16:21

no its controlled via the CIM.

**Gayno** · 7th December 2010, 21:01

Hmm OK, so the buttons connect to the CIM, then the CIM to the stereo?

Or is the CIM then on the CANBUS??

**yysnet** · 7th December 2010, 21:31

Cim-midcanbus-screen & stereo

**Gayno** · 8th December 2010, 00:32

So to get this to work, I'm going to have to tap into the buttons before the CIM then?

**ChrisBilly** · 8th December 2010, 02:19

I think both sets of three buttons have three wires; illumination, constant voltage and earth. I'm not 100% but I think each button has a resistor that alters the constant voltage when pressed, the computer then converts the altered current into a command for the device.
It seems the only old fashioned switches (directly connected to the device it controls) in the vec c are on the interior light.

**Robsey** · 10th December 2010, 01:38

True route is believe it or not...

Buttons to CIM unit ( different resistence value for each button - provides a different signal voltage to the CIM)

CIM unit to Instrument cluster - Via Low Speed CAN (Data Packet stream)

Instrument Cluster to BCM (Body Control Modue) - Via Low Speed CAN (Data Packet stream)

BCM to Display - Via Mid Speed CAN (Data Packet stream)

Display to Head unit - Via Mid Speed CAN (Data Packet stream)

Note also that a theoretical zero ohm switch closure will sound the horn!!

For wheel control set-ups that are programmed incorrectly, any switch closure will sound the horn.

**UncleMelon** · 15th December 2010, 12:21

Is there any amount of fiddling that can get the thumb wheel style controls to work on the old 6 button style wheel?

I hate those 6 buttons the newer controls looked so much better

**kenp** · 15th December 2010, 12:38

I know you can, if you change the CIM to a newer one.. dont know if its just a code change on the old...

**Robsey** · 16th December 2010, 01:02

Originally Posted by kenp

I know you can, if you change the CIM to a newer one.. dont know if its just a code change on the old...

I run a 2005 CD70 and GID with a late 2003 CIM module and 2003 BCM.
(but in a 1994 Cavalier)

It just requires the variance configuration of the CIM to be reprogrammed to scrollers rather than buttons... I think the radio should allow this also.