Those may be good candidates for your ignition-controlled line.
You'll still want to measure the voltage with the key on and off to be certain it will trigger the M3.
Hello all, I am endeavoring to install my carpc in my 2010 vw golf 2.5. The latest problem I am having is getting the ignition to turn the mobo on and off with the jumper in the m3-atx power supply. I narrowed down the switched wire in the harness but when off provides 12 volts and when on provides 4 volts. I tested with the stock headunit and this is definitely the wire that turns the head unit on and off. I read in another thread that if the ignition wire is like this then you have to get a switched wire elsewhere from the fusebox or the cigerette lighter.
Since my cigerette lighter turns on and off with the ignition would this be suitable as the ignition wire turn on and off? Is there any cons with using this? Thanks in advance
Thanks for the reply... I will go ahead and measure it before I disassemble it any further. Does anyone know how much power the m3-atx requires on the ignition to start? I measure another wire which seems to be a canbus wire and it puts out .7v when the ignition is on but that doesn't seem to be enough
all power supplies require a +12v input, and should not consume any more then about 200mA on the ignition line.
My OLD 2001 Mitsubishi Eclipse GT:
"The Project That Never Ended, until it did"
next project? subaru brz
The ignition wire from the M3 PSU is a trigger wire that works like this. When you turn your ignition switch on the M3 detects that +12 volts has been supplied to the ignition wire and sends a pulse to the motherboard's power switch connector and your carputer will boot up. When you turn your ignition switch off the M3 detects the loss of this +12 volts and sends a pulse to the power switch connector on the motherboard and your carputer will shut down. So what you want is a wire that supplies +12 volts when you turn the ignition switch on and zero volts when you turn the ignition switch off.
Reading your original post you said you found the wire that switches your factory fitted head unit on and off. I interpreted what you wrote to mean that it supplies +12 volts with the ignition switch off and +4 volts with the ignition switch on. If that is the case then this wire is not the one to use as the voltages are the wrong way around, as per my explanation above.
Most cars have the same as you mentioned in that the cigerette lighter is powered only when the ingition switch is on. You could splice the ignition wire from your M3 PSU to this wire, which is what I did for my carputer, if I remember correctly. As for pros or cons, I can't think of any.
Hope this isn't too late to be of any use to you. Good luck with your carputer.