Car Steering Wheel Controls

Discussion in 'The Projects Forum' started by JRMN, Feb 17, 2011.

  1. JRMN

    Thread Starter New Member

    Feb 17, 2011
    3
    0
    A while back I installed an aftermarket radio in my car to retain my steering wheel control buttons I purchased a Pac-Audio SWI-ECL2. Since I am now working on another Arduino car project, I would like to get rid of the SWI-ECL2.

    http://www.pac-audio.com/productDetails.aspx?ProductId=209&CategoryID=29

    The wiring for the SWI-ECL2 is straight forward; I have five steering wheel buttons (vol. up, up, mode, vol. down and down). The harness for the steering wheel control buttons has three wires (Pin 26, Pin 27 and Pin 29). At the end of Pin 26 there is a 47 ohm resistor, at the end of Pin 27 there is a 150 ohm resistor and Pin 29 is connected to ground. Pin's 26 and 27 connects to a single white wire going into the SWI-ECL2. The SWI-ECL2 and the radio are connected by two wires.

    Originally I thought that codes were being sent from the SWI-ECL2 to the car radio, however, after doing some research on the internet, I think it’s a simple resistor ladder. I also found out that I might be able to connect directly to the car radio, bypassing the SWI-ECL2 altogether. So I disconnected the SWI-ECL2 and connected Pins 26 and 27 directly to the two wires of the car radio and then connected pin 29 to ground. The good news is it did work; I am able to control my car radio with my steering wheel control buttons. However, the bad news is the radio isn’t being controlled properly. An example would be if I press the mode button on my steering wheel, the volume might go up.

    I’ve been reading up on resistor ladders. I also found this instructable.com on how to access five buttons through one Arduino input, which is exactly the same interface my steering wheel controls.

    http://www.instructables.com/id/How-to-access-5-buttons-through-1-Arduino-input/

    I’m not sure I fully understand what’s going on and if I did, I might be able to figure out how to wire my steering wheel controls up to my car radio.

    I really would appreciate some guidance/help/suggestions on how I should proceed.

    Thanks in advance.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    One important question - does this mod interfere with the air bag?

    Are you limited to only the one button? That one button methodology is trying to use the A to D converter to read voltages that are unique to each button being pressed. The fun part is if more than one gets pressed.

    If you can devote 5 pins, the problem gets easier.
     
  3. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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  4. JRMN

    Thread Starter New Member

    Feb 17, 2011
    3
    0
    @beenthere. I don't understand what you mean by mod, but no, wiring directly to the car radio doesn't interfere with the airbag.

    I believe mode, up, and vol. up are all on the same wire (pin 26). And I think down and vol. down are all on another wire (pin 27). Although vol. down could be on a separate wire (pin 29). I say that because when I hooked up the multimeter (checking resistors) I didn't get a hit from vol. down.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Mod = modification.
     
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