Stable ADC readings

[mister_e]

The link I provided was about the OUTPUT not the input. It show how to connect your resistor and how to code it.

your whole system to the car should be more than 6 wire... but 3 of them should already be GND or +5v/+12V.

Plug the steering wires, push on each button, for each button you have a diffferent ADC reading.

OR use a multimeter and measure the resistor value when you push on a single button.... also when you don't push on any button. From there we can also work out a solution.

Also, we still have NO information about your radio, no brand, no model no nothing. At least do you know the resistor value needed for each function?