/diy/ - Do It Yourself

[Anonymous No.1370649]

I posted this question in /o/ and nobody could help, and I tried /g/ but nobody bothered with a reply.

I'm looking to add an Arduino based keypad/codelock ignition system to my car, but I also want to keep the old key system in place as a backup incase the Arduino fails for some reason.

I've looked at the circuit diagram of the ignition system and it looks like an on/off switch, but I know it's not that simple, because the key system is supposed to use 2 switches, one for the electronics, such as the fuel pump and sensors and such, and the other for the starter motor.

I don't know much about cars, I can service it and change a tyre, that's about it. I'm a programmer by profession, used to be a welder (not a very good one at that).

Does anyone know if I can add an ignition system like that? If so, where should I be looking and what should I be looking out for?

[Anonymous No.1370656]

>where should I be looking and what should I be looking out for?
https://www.youtube.com/results?search_query=how+to+use+multimeter
https://www.youtube.com/results?search_query=how+ignition+switch+works

[Anonymous No.1370657]

>>1370649
Place relays across the accessory and starter lines, use microcontroller to drive relays in appropriate sequence. Not hard.

[Anonymous No.1370699]

>>1370649100% dependent on what kind of car this is and what year. any sort of networked modules and the difficulty goes close to impossible.

[Anonymous No.1370716]

>>1370649
Keys have multiple positions, at the basic level there is off, run, start. When you turn a key you turn it as far as it will go to start, when the engine catches you let the key go and it jumps back a little into run.
Right? Anyone who has used a car knows this.
So the key switch has a few different connectors and they are connected or not when the key is in different positions.
If you can find a service manual for your car it will tell you what connections are connected to each other when the key is in each position, or go to a scrap yard and get a spare and test it out yourself with a continuity tester.
The difficult part is knowing when the engine is running to release the starter.
If the car is ecu controlled you might get a signal from obd2 to tell you when the ecu is happy that the car is running, if its a carburettor/magneto/spark type affair then I don't know what to tell you, maybe you could monitor the spark or vibration of the engine, maybe they change as the motor is turning over.
If you have immobilizer it will complicate things.

[Anonymous No.1370717]

>>1370699
It's a 2007 Daihatsu materia. This is the circuit diagram I got from the workshop book for the car

[Anonymous No.1370721]

>>1370716
Thanks man, rather clear explanation.

The car has no immobiliser, just got the service manual, I'm looking through it now. Seems to only have the bare basic information though, and it's not a very common car around here. I'll see if I can get a spare ignition system to play around with and experiment.

I'm thinking of having an engine start button if the key is out and the code was entered correctly. My problem will be switching the car off. Haven't given that any thought yet. But a second button to switch off should work too.

[Anonymous No.1370742]

Don't forget that the car also has a mechanical lock that keeps the steering wheel from being turned without the key being in a certain position.

[Anonymous No.1370758]

>>1370742
Shit. I forgot about that.

[Anonymous No.1370767]

>>1370649
I totally re-wire agricultural motors sometimes

its going to be one hell of a wiring project
everything under the dash is all packed in there and tied up tight
newer vehicles got about 100 wires all wrapped together

your ignition system has to get power to a minimum of 2 things but I am assuming you have an electric fuel pump
1 power to ignition
2 starter
and fuel pump if you got an electric pump

getting power to the starter and ignition don't sound too hard but you should expect some issues and a severe lack of room to work

when I re-wire stuff I do it very simple and easy but it sounds like you aint gonna do that
I can get a piece of machinery or an old truck working in maybe an hour
I do 1 push button switch and 1 on/off switch
push button switch has wire from battery to switch and a wire from switch to starter solenoid
other switch is battery to switch and switch to ignition


and please remember and think about this
if both of your ignitions are wired together its very possible that if one don't work then they both wont work
sounds stupid to me I would never do it but whatever you want

[Anonymous No.1370817]

>>1370767
Alright, thanks for the advice man.

I'm going to try and wire it in a way that they don't interfere with each other, itbi can. It one is off whole the other is off, it shouldn't affect each other I think. But I'll play around with a spare system or get a scrapyard car with a motor that turns (doesn't necessarily have to start) and play around a bit

[Anonymous No.1370828]

>>1370742
Most owners of older cars retrofitted with a diy 'push to start' system just leave the key in the column so the steering wheel is unlocked, but not so that the electrical switches are closed.

Most cars key clusters operate three 'switches,' not two: Accessory, Engine power, and start. Pretty simple business to just throw a relay across each of those and control with an arduino. I 'deleted' the steering column key cluster in a 2005 Scion and just replaced it with two toggle switches (acc/engine) and a momentary (starter). I'd be surprised if your materia was any more complicated.

Good luck homie; be brave--any affordable cars made before 2013 are generally pretty simple, all things considered.