Steering wheel controls

Inspired by a couple other posts I endeavored to add paddle shifters to my steering wheel and it turned out very well. I 3d printed some spacers to set the shifters a little better. I also wanted to repurpose my steering wheel tip controls for radio controls and figured I would have to add wires to the wheel, this is why I was looking for a backup clock spring in a previous post. My radio, a continental has a 2 wire control system, ground and resistance to ground (I think). So I placed continental guided resistor levels in line for the buttons giving me volume up and down on the left tip, and seek up (and down if wanted) on the right tip. Upon further progress I discovered my clock spring an unused wire! So the steering wheel controls for the radio need no further help to work other than connecting the resistors to the wire inside the wheel and the 3.5mm jack to the same wire outside the wheel. Here is where I get my dilemma. Since I was planning on adding wires to a clock spring I was going to add 2 in for a mute button for the radar detector and use the Rt tip - for that function. I�ve isolated to ground from the Rt tip down so I doesn�t interfere with the other and set it up so it can take 2 wires to be a mute button. With my new revelation of not needing to add wires to get radio controls should I abort the radar detector mute and just have seek up and seek down? Where should I mount the mute button? or should I see if I can hack the clock spring I got off eBay for $80?

Here is the inside of the clock spring. 3 revolutions lock to lock on a 996. 4 revolutions allowed by the clock spring 15 revolutions of ribbon wire at center with 7 conductors.

It’s busy, but I was able to safely get paddle shifters on the original grounding circuit. Steering wheel controls using specified resistors for the Continental stereo for volume up and volume down and seek up. And I repurposed one of the tip buttons for a mute control for the radar detector. All tests according to the multi meter work… we’ll see once the airbag is back in and I power it up 😬 Happy to answer any questions.

Ok, So I will use this as a data dump since everything works well - In case anyone else wants to use a similar radio and button set up: I used a potentiometer on a breadboard and some jumper wires to dial in the resistance readings for the radio. The Radio in question is a Continental CD7416U-OR, I assume any of the Continental CD radios will work, this one has usb, mp3 and wma, I opted out of Bluetooth because reasons, probably similar reasons to not wanting a big double din touch screen. I find the Continental radios to be much more modern but still period similar in style and aesthetically good. The radio is controlled on its own 5v system with resistance to ground using a 5V key 1 wire and a supplied ground to complete the 5V circuit. It is not good to use the body ground due to noise and interference with the 12v and all the other electricity flowing through that although it did produce some functionality with the car not running. The system is basically a reduced voltage reading using stepped or ladder resistance increases. With the potentiometer, breadboard, and multimeter all connected at the same time, I could read real time resistances and actual outcomes of button presses at those resistances, here is what I found: 50-100 ohm is volume down 110-170 ohm is volume up 180-280 ohm is source change 290-390 ohm is tune up, and if held for 1.5 seconds seek to the next station 390-620 ohm is tune down and if held for 1.5 seconds seek to lower station 670-1050 ohm is next preset, and only on that current preset band (since there are 3 FM bands, in only cycles through the 6 presets on FM2 if you are on FM2) Beyond 1050 ohm the resistance is high enough that the voltage drop can't get much lower for the radio to distinguish so there were no functions above 1050 ohms that I was able to find up to about 2200 ohms which is where I quit.