Details of how the steering wheel controls work
Details of how the steering wheel controls work Could someone explain to me exactly how the steering wheel controls work?
If I hook the positive side of a multimeter up to the steering wheel control wire and the black side of the multimeter to a ground, I get voltages under 5 volts when I press buttons.
If I take the steering wheel wire out of the harness, hook the positive side up to the steering wheel wire, and hook the black wire up to a ground, I get like 11 volts. It doesn't change based on which button is pressed either.
So I'm confused. It doesn't look like the steering wheel wire is directly responsible for the different voltages. It only provides different voltages when it is attached to the harness.
This is a problem because I would like to disconnect the steering wheel controls from the head unit and use them with another piece of hardware.
If I hook the positive side of a multimeter up to the steering wheel control wire and the black side of the multimeter to a ground, I get voltages under 5 volts when I press buttons.
If I take the steering wheel wire out of the harness, hook the positive side up to the steering wheel wire, and hook the black wire up to a ground, I get like 11 volts. It doesn't change based on which button is pressed either.
So I'm confused. It doesn't look like the steering wheel wire is directly responsible for the different voltages. It only provides different voltages when it is attached to the harness.
This is a problem because I would like to disconnect the steering wheel controls from the head unit and use them with another piece of hardware.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
The steering wheel controls have a single power input and an output that goes to the head unit. Each switch in the wheel is connected to a different resistor so the head unit can determine which switch (or combination of switches) is pressed by the voltage drop across the resistors.
If you want to use the switches for some other purpose you'll have to build a logic circuit that can determine which resistor(s) are in the circuit at any time so that it can respond to the switches.
If you want to use the switches for some other purpose you'll have to build a logic circuit that can determine which resistor(s) are in the circuit at any time so that it can respond to the switches.
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
If you have to ask then it's beyond your capabilities. You would need a modeling circuit board (called a "breadboard") and logic chips, resistors, capacitors, diodes, etc. to build an electronic circuit that toggles micro-relays or something similar as on/off circuits based on the resistance measured from the steering wheel switches.
I've been looking into this a little more and I think the steering wheel controls have have another wire somewhere. Maybe it's just a ground I'm not really sure. The FAQ only shows one wire for the steering wheel controls though? I've never taken the steering wheel controls apart to look for myself. Have any of you guys?
Joined: Nov 2003
Posts: 11,331
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Nope...no other wire. It has a wire providing power input to the switches and a wire that goes from the switches to the radio. The radio compares the voltage it reads on the switch output wire to reference voltage it gets from the battery to determine how much resistance has been added to the circuit by a switch being pressed.
