112233

Hello,

I noticed that the buttons at the steering wheel only function when the engine runs. If the engine is off, the buttons behave erratic.
I first pulled the clockspring and measured it, but it is working. Found a document that describes the function of the buttons it says that the way the buttons work is like an resistor array, so the voltage defines which button is pressed.

Where should I look now?

Thanks

C230 Sport Coup

Could be cold solder joints.
Mine quit working and I found somewhere on the web
how to fix it, resolder cold solder joints.
Sorry, I don't know where now.
Be sure your battery is good.

112233

I have seen they sell a steering wheel wire harness for rebuild, that could be a hint. Battery is a good point, I have 12.4V at the battery and to test it, I connected the battery with a charger, but no change.
Positive voltage is coming from the SAM and negative from a connector in the right footwell. I think I will pull the steering wheel again and measure the resistance of the cables. A better way would be to measure the voltage, no idea to get access to the connector with steering wheel in place. .

112233

I measured the stand-by current, it is below 20 mA (connect multimeter instead of the negative cable from the battery, max.amp was 0.5A falling down to 16 mA after 30 minutes), Battery is ok.
I think I will buy a used clockspring,

slammer111

Before just throwing random parts at the car, personally I would remove the steering wheel button assemblies and reflow all the solder. Costs nothing to try this first.