How does modern power window control work?

[VeeFource]

Thought I'd use the Christmas break as an opportunity to do a little lighting project on my Ibiza mk5. I'm looking to make my door bins illuminated and an obvious power source option are the illuminated window switches on the doors, or so I thought..

Unlike previous switches I've come across, these only appear to have 3 wires despite the fact they have one touch up and down as well as being illuminated (with variable brightness via main dimmer). So how is all this functionality possible with only three wires as I'm guessing the switch will only have simple contacts with no sophisticated electronics in there? I've trawled the net for over an hour for a solution but to no avail.

Thanks in advance :-)

[shovelheadrob]

Most things are controlled by a bcm (body control module) via canbus. You can no longer just run extra things in this way.

[trashbat]

At a guess: supply power on one pin, use it for the illumination, return on the second. Supply voltage determines the brightness.

Also have the switch return on the third pin when pressed, low voltage for down and high for up. Nothing complicated, just a resistor. Body computer senses the circuit and has the logic for performing the action.

Edited by trashbat on Thursday 26th December 19:24

[VeeFource]

Ended up testing the switch and you're about right with that trashbat. The rocker switch has 3 resistors in it to vary the voltage for each of the four switch positions on the supply wire from the window controller. The other wire comes from the dimmer and both circuits are connected to ground.

Thankfully it should mean I can use the illumination circuit without any issues

Edited by VeeFource on Thursday 26th December 23:55

[Rich_W]

Is there not a control unit in there with a multiplug that you could use rather than messing around with the switch circuit?

[VeeFource]

Rich_W said:

Is there not a control unit in there with a multiplug that you could use rather than messing around with the switch circuit?

Needed a feed for illumination on each of the doors which is why I used the switches rather than a remote control module.

All done now, looks saweeet

[Ozzie Osmond]

shovelheadrob said:

Most things are controlled by a bcm (body control module) via canbus. You can no longer just run extra things in this way.

^^^ This.

Read it.

Pay attention!

[MangledMetal]

Just a thought, electric mirrors maybe an easier source of power ? They're normally a lot simpler, no fancy electrics.

[VeeFource]

Ozzie Osmond said:

shovelheadrob said:

Most things are controlled by a bcm (body control module) via canbus. You can no longer just run extra things in this way.

^^^ This.

Read it.

Pay attention!

He said "most" not all things! The window switches are actually external to any data bus as are most of the illumination circuits. Which is why I was able to run my extra things off it successfully.

So it seems like you're the one that needs to 'pay attention'!

MangledMetal said:

Just a thought, electric mirrors maybe an easier source of power ? They're normally a lot simpler, no fancy electrics.

Electric mirrors only get power when they need to either move or be heated, there's no constant source of power unfortunately. Thanks anyways though :-)