Getting the steering wheel buttons to work with the Seicane radio

Discussion in 'Electronics' started by Fubar, Aug 10, 2019.

  1. Fubar

    Fubar New Member

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    I got this Seicane Android radio for my 2002 KJ Liberty because it is the same shape/size as the factory unit and fits on the existing bezel with no need for modifications.

    I won't bother describing the installation, because it is quite straightforward. Adapters for factory harness and antenna are included so it is pretty much plug-and-play.

    What is not so straightforward is how to get the steering wheel controls to work with this unit.

    Good news is that you won't need a special CANbus decoder box.

    However a small modification is required because as it turns out, the steering wheel button voltage is slightly higher than what the Seicane can sense.

    First step is to remove the steering column plastic cover. It is held by two torx T20 screws

    Once you get this off, this is what you'll see:

    steering.jpg

    A yellow and a white connector.

    The wire that corresponds to the steering wheel buttons is the middle one on the white connector (red with blue stripe)

    conn.jpg


    Normally, we would splice the wire marked KEY 1 or KEY 2 from the Seicane harness to this red with blue stripe wire and be done with it.

    I did just that, and while it seemed to work, I couldn't map the keys that are normally for volume up/down on the SWC app.

    swc.JPG


    I noticed that the voltage generated on the red/blue stripe wire when those two buttons are pressed is the highest relative to other buttons.

    Here are the voltages that correspond to each button:

    voltages.jpg

    4.99 Volts when no button is pressed, 3.49 when Volume Up is pressed and 4.25 for Volume Down

    Apparently the Seicane works on 3.3 Volts internally so it can't recognize anything above that.

    So I used a potentiometer between the steering wheel wire and Seicane to drop the voltage. I set it at the midpoint, which means all voltages would be halved.

    And it worked! All buttons could be mapped on the SWC application.

    Here's my test apparatus, the potentiometer shown by the red arrow

    potentiometer.jpg

    pot.jpg


    I didn't have the time to make permanent connections, so I removed all extra wiring and put the radio back in.

    If I find some time tomorrow, I will make a simple resistive divider (more reliable than a potentiometer) and splice it on the steering wheel wire. I'll post detailed photos and maybe a video.
     
  2. Fubar

    Fubar New Member

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    This is what the resistive voltage divider should look like

    divider.JPG

    Two resistors of equal value will divide voltage by 2. The value isn't super important, anything from 10K to 100K should work.
     
  3. Fubar

    Fubar New Member

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    Ok, first let's make the ground connection. One way would be to splice it on the main harness, but I chose a more creative way:

    gnd1.jpg
    I am taking the black wire from an old computer PSU.
    gnd2.jpg

    My crimping tool

    gnd3.jpg
    gnd4.jpg
    Screwed it on the side of the unit!
     
  4. Fubar

    Fubar New Member

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    Now let's splice a wire on the steering wheel red/blue stripe wire.

    wire1.jpg

    This is going to be the extra length of wire to be spliced

    wire2.jpg
    Harness wire cut and ends stripped

    wire3.jpg

    One end crimped

    wire4.jpg
    Both ends crimped. I then wrapped it with some electrical tape to keep everything in place
     
  5. Fubar

    Fubar New Member

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    Now to make the voltage divider and final connections. These are the resistors I'm using, plain old 1/4W, 12Kohm ones.

    div1.jpg
    Soldering one resistor on the green wire

    div2.jpg
    And this is what the final result should look like

    div3.jpg

    The other resistor soldered on the ground wire and the KEY 1 wire soldered on the mid point between the two resistors.

    Just remember to slide some heatshrink before making the final solder!
     
  6. Fubar

    Fubar New Member

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