Quote:
Originally Posted by gosi
Hi guys,
sorry to revive an old thread, but at least the coronavirus is good for one thing - giving me time to fiddle with my car.  I've made some progress on this idea.
I've disassembled the steering wheel to see how the controls work. The blank buttons have a working circuit underneath them, which is good, the bad news is that there are two LED's missing, which means you'd have to find the correct LED's and solder them on, or the buttons wouldn't light up at night. A minor issue, but still.
The left button cluster (where the blanks are) has analog pins that go to the right cluster, where there is presumably a LIN slave that then sends a digital signal through the steering wheel clock spring, at which point it is useless to us. To get working buttons, you need to intercept the analog signal before it gets to the LIN node in the steering wheel.
I've been able to find the correct pins for both blank buttons, one is pin 1 and 6, the other pin 3,4 (see attachment). Now it's a matter splicing the 4 wires and finding a way to route them through the steering wheel separately. I don't think there is a way to route the wires other than going through the clock spring (that's the thing that allows you to turn the wheel without severing the wires). There are two connectors on the steering wheel that go through the spring. One is for the LIN stuff and has one empty pin on it and the other is for the airbag, which has 4 empty pins. If you have a heated steering wheel/or lane assist, you have an additional connector AFAIK. I don't so I don't know if there are any empty pins there...
I've seen people retrofit a heated steering wheel and wire it through the empty pins on the airbag connector instead of buying a new clock spring. You could do the same thing here, and it would be just 2 buttons instead of a heating element, but I'm still a bit unsure about doing that, since I don't want an airbag exploding in my face  Another option would be to buy a new clock spring which has the additional connector for the heated steering wheel function and you could use that, but I'm guessing that would be pricey.
Anyway this is doable and I just need the right pins to fit the connectors and I'll be all set. I will be using the buttons to control my P3 gauge, but they could be used for anything What do you guys think? |
I know this is a bit late - but did you record the voltage being outputted by the pins? If not I'll probably need to go measure it with the battery plugged in (always makes me a bit nervous with the airbag there - is it okay to reconnect the battery and turn on the car with the airbag unplugged?)
EDIT: I would assume it's 12V, but dunno if it's down-converted for the switches and such. Although, on further thought - you say that the each switch is related to two pins (1 and 6 for example) - they don't share a common ground? If it's just a simple switch, then that could make my job easier as the voltage will come from my input.