Code immobilizer?

**smilykoch** · 09-22-2009, 08:07 AM

Hey..

I was wondering if it is possible to make a software/hardware solution for a carpc that does the following? :

When you put your key in your car and turns on ignition power the carpc turns on, the first screen you see would be a screen with 0-9 and somthing like "submit" and "C" - you would then need to press a 4 digit code right to deactivate the immobilizer and the screen would continue to something like CF frontpage.

So it would require the 4 digit code to be right before you can start the car? and then something like 3 wrong tries would require you to wait like 10 min before you can start again ?

It would be really cool..
you know.. i mean like, fx some pug 106 has the code part of it, but just not in the carpc..?

Hope you will be able to help me out here..
(know its not newbie, but dident know where to drop the post..)

Smilykoch.

**Bugbyte** · 09-22-2009, 08:19 AM

This is possible but the question is whether or not you want to trust it. Several issues:
1. If the PC doesn't start, you car doesn't start. This WILL happen to you.
2. Unless the PC is on standby, startup times are around a minute. You can probably get that down to perhaps 20 seconds, maybe a little less. Do you want to wait that long?
3. In a low battery situation, your PC will suck a lot of juice that could be used for starting. This could easily happen in the winter if your battery is older.
4. Your PC will need to survive crank every time to make sure the car doesn't shut off when starting.

These are not insurmountable problems but I'd bet money there will be times when your car will strand you somewhere. Most likely on an important work day when you have a presentation to the higher ups.

**smilykoch** · 09-22-2009, 08:28 AM

hmmm... okay, i see what you mean..

The nr 2 i have no probs with, the carpc is connected to my central lock, so when i unlock the doors the carpc starts, so its nearly fully started when i am in the car..

The nr 3 also, i have an extra battery because i have a pretty big power use ;b hehe..

I see the nr 1.. :s wouldn't it be possible to make some sort of safety for this, something like being able to work around the carpc if it doesn't start ? an extra keyboard with 0-9 ? or just a plug to plug the keyboard in?

What do you mean with nr 4? didn't quite understand? ;o

**Bugbyte** · 09-22-2009, 09:53 PM

When you start the car (that is, crank the starter) the voltage drops considerably. Modern intelligent DC-DC power supplies attempt to compensate for this but it is still possible for the voltage to drop too low to keep the PC alive when you crank the starter. The PC will restart just like you pressed the reset switch.

Depending on how the immobilizer system is designed, this could cause your car to shut off.

**malcom2073** · 09-22-2009, 09:59 PM

If you want to do something like that, personally I'd buy a serially controlled graphical touchscreen, and run it off a microcontroller. Take the PC entirely out of the loop. a Carputer is not something you want to trust with your life (what if you had to get to the hospital?), or even your job (Sorry boss I was late, my car wouldn't let me start it) with. It's a cool idea, but using a PC is just impractical. You're adding levels of failure to an already fragile system.

**smilykoch** · 09-23-2009, 02:39 AM

serially controlled graphical touchscreen?? perhaps a link? how does that system works and would i still be able to run the carpc on that screen after the car has started ? or would it be a second screen ?

Ahh.. i see the problem with the voltage.. :s not that cool.. any ideas on how to make the system work so i could make something like this.. (its just an idea, i just wanted to know if its possible. And how? so any solutions on how to solve those problems properly?)

**justchat_1** · 09-23-2009, 05:44 AM

Use a latching relay with a hidden override button. If the crank voltage drop causes the PC to reboot the car will stay running. In the event things go wrong you'll have that hidden button you can use to still be able to get where you need to go.

ediit:
and for obvious safety reasons this type of system should be tied into the start circuit not the run circuit.

**smilykoch** · 09-23-2009, 05:53 AM

okay.. so you would just insert a relay and then make the software so the relay is only active when the code is pressed right..? in that way you could still use a normal car alarm with it.. then just put the relay on the car start circuit ? would that work?

**black_mamba** · 09-24-2009, 04:46 PM

Just like justchat said. Use a relay that will bypass the computer and just hide the switch for it. If, for any reason, the computer is not working, just hold the switch that will turn on the relay that bypasses the computer. How you setup the relay would totally depend on how your immobilzer is designed (though I think most are just a relay themselves). I've never used an "immobilzer" product before, so I don't know how they work, but I have installed more than my share of car alarms and stereos to know that this is easy enough.

If you have a link to the immobilzer you are thinking of using that might give more insight as to what can be done with it.

**justchat_1** · 09-24-2009, 04:52 PM

Yes thats the basic idea...

My comment was about using a latching relay....latching relays have an on pulse and an off pulse instead of constant power to keep them switched. This means when the computer sends the on-pulse even if the computer shuts off right after, the car can still be started. Then when the computer is shutting down it sends the off pulse to the relay to immobilize the car again.