My computer hasn't even arrived yet, so this is still firmly in the planning stages. Here's a bit of background: I'll be "installing" a tablet PC in my MCS. Since it takes a little while for Windows to cold boot, it would be neat if I could rig things so the computer would power itself on as soon as I unlock the doors. By the time I was buckled in and driving, the PC would hopefully be ready to rock. Since this tablet is battery powered like a laptop, I can't just supply it with power and have it start. I've already sourced a little homebuilt module that when wired to the computer's power switch, will simulate a button press and thus cause it to power on. The button-press-simulation happens every time the module sees a wire go from 0v to 12v.

So, if I wired the module to a "switched" circuit in my MCS, a simulated button press would occur when I turned the key on. That's great, but I'd like to have this happen before I get in the car. I could also very easily wire it to one of the interior lights ("dome lights"), which of course come on when the doors are unlocked. The lights come on lots of other times as well, but that would probably be okay because you can tell Windows to ignore any subsequent presses of the power button after the OS has loaded. Still, it still seems a little ghetto.

The best way to wire it would be to somehow trigger off of the unlocking circuitry itself. Driver's door, I guess. But, I don't know how to acomplish this. Can anyone give me some advice? The way the module is set up right now, it needs to "see" 12v for the duration of the "button press". About a half of a second. A shorter blast of 12v might also work, but there's probably a lower limit. (The module just closes a relay that shorts together the contacts of the computer's power switch. I'm not sure how fast that happens.)

So that's it. Does anybody know where I can tap into a 12v wire that only goes hot when the driver's door is being unlocked? Thanks in advance!

 

I once read that the CD changer is powered up when the doors are unlocked, in preparation for use - but I give no guarantee of that being correct!

There is a "remote auto-close-windows" gadget which taps into the lock & unlock signals (and others); might give you some wiring clues ... see:
http://outmotoring.com/remote_contro...up_module.html

 

Have you thought about an interface with the key fob? Press the button and turn it on with the unlocking of the doors

 

ScottinBend: I hadn't thought about trying to detect the transmissions from the keyfob directly. That sounds difficult, unless someone already sells a doohickey that does that. Have you heard of people doing this?

GBMINI: Ooo, that theory about the CD changer sounds interesting. I'll try to track that down. If nothing else, it should be pretty easy to get at those connectors with a multimeter. I'll also check out that thread you linked. Thanks!

 

I was thinking you could somehow find the lead that powers the locking mechanism and switch the carputer from that.

 

Yes indeedy. This set of instructions for one of those window modules has some excellent clues. No color codes for the wires coming out of the door however...
..
According to that, I might not even need that custom module thingie that generates a short pulse... to energize the relay... that closes the switch on the computer. Well okay, I still need the relay part, but I don't need the tricky bit with the capacitor that serves to limit the time the relay stays energized. The pulse of 12V that's going to the door-unlock motor looks perfect for a quick closing of the relay.

Ah! The wire color codes can be found in this doc. Looks like I'll just need to find the blue wire that comes from the door, and tap into it. Question, where's the other end of this blue wire coming from. Isn't there a box down in the right-side foot well that handles some of the locking/unlocking logic?

 

Sounds like you're on the right track, Dave. Kudos on the ingenuity.
Question - what do you use the computer for? Other than Nav, I can't think of a reason to have a computer in the car...

 

There's at least one good "how to" to install that OutMotoring thingy ... search ...
https://www.northamericanmotoring.co...=remote+window
Lots of good pics that might help you track down the needed wires

 

Cool.....glad I could help !

The control "box" is the Body Control Module. You could probably check the Bentley manual for its wiring diagram.

 

Hi, Eric. Sorry to be so slow in my reply. My computer arrived, and I've been playing with it.

The computer (once I figure out how to mount it in the car) will primarily be used as an MP3 player. As you mentioned, I'll also have it set up for GPS navigation. (Including Google Earth with overlaid real-time traffic reports.) That implies internet access, so I'll be able to do all of that browsing/searching/emailing/chatting/net-radio kind of stuff if I so desire, although I don't imagine that will be a major activity. Once I get a Bluetooth enabled cell phone, the computer will act as a hands-free "car kit". Displaying incoming calls, acting as a speakerphone, auto-muting the music, etc, all without me ever touching the phone on my belt. I'm also hoping to mount a forward facing infrared camera in the car, and that video will be fed into the computer for realtime viewing and recording. Also, I will be able to monitor what the car is doing via an OBD-II interface, and maybe, someday, some dedicated sensors. Then of course, there's all those passenger-entertainment functions: Games, DVDs, eBooks. Again, I doubt I'll actually need much of that, but it's trivial to add once you've got the computer in the car.

That's it, but I'm sure I'll be able to think of some other stuff eventually!

 

Dave, what were you finally able to do for the power switch?

 

Dave,

Where are you going to mount the PC in car? I was thinking about a 7 inch touch screen, but a Tablet PC now that is big.

 

ScottenBend: I went ahead and ordered (and have received) that relay module. It closes a relay whenever it "sees" 12 volts. I can hopefully use the wire that feeds the MINI's driver-door lock un-locker to supply that 12 volts. I'll have to open up the tablet and connect the two wires from that relay to the existing switch. In theory, that will result in the tablet thinking that its switch has been pushed, every time I unlock my door.

I'm still trying to figure out how to mount the tablet, so I haven't actually tried any of that.

MiniDrew: Yeah, a 12" screen is decently big, as compared to "normal" carputers. Those are usually 7" or 8". But, they're that small so they can fit within the same width dash opening as a car stereo. I didn't really see a good way to fit even a small screen into the MINI dash "stack", so I figured, "What the heck, go big!" My eyes aren't the best for closeup work, so big is good. Plus, I'm getting double use out of the tablet by using to surf the net from bed. There again, I figured there was no downside to the larger screen. (And it's still smaller than most laptop screens.)

I plan on mounting the tablet on some sort of arm. Something like this and one of these. Hopefully, I'll be able to rig it so that the tablet will sort of "float" somewhere to the right side of the speedometer. The tricky part will be finding a place for the base of the arm that doesn't interfere with the passenger's leg room, or the ability to slide the seat forward. (The dang handle for the slider is right where I'd normally want to put the "pole".)

Research continues....