cb944

OK.. this probably won't appeal to everyone, but I spent about 14 hours straight yesterday wiring up a new alarm and a push-button start system, thought I would share my experience so far.

Basically, I got one of these RFID passive-entry alarm systems. This is the one I got:

http://www.ultimatecarparts.co.uk/pa...ser-p-204.html

I thought it looked pretty neat. However, I figured that if I was going to have a passive entry alarm, it was pretty pointless if I then had to get my keys out of my pocket to actually start the car.

Obviously, there are a lot of hurdles to overcome. The main ones I still have to deal with are a) what to do with the steering lock and b) the fact I don't actually have central locking yet.

Yeah, no central locking. Anyway, that's the minor details out of the way

I bought a fairly standard push-button start kit off eBay. The kit came with wiring that would fire the starter. Again, that seems fairly pointless as you still need to turn the key to switch on the ignition. What's the point in that? You might as well just turn the key a bit further to start the car. Of course, the major problem with not having that is you need some way to kill the engine once it's started. Obviously, the sensible thing would be to just have a kill switch, but I really wanted this to operate all on the one button.

So, I designed a circuit that uses a latching relay to switch the function of the starter with each press of the button. So, I assumed I'd be able to do this:

1. Use the alarm system to switch on the ignition/acc when I got near the car. I'd put an override switch in so I could disable this function if I was going to be sitting in the car a long time and didn't want the ignition to remain on.

2. With the ignition engaged, the first press of the push button will fire the starter. You keep your finger on the starter until the engine starts.

3. When you want to cut the ignition, you press the start button again. This has the effect of switching the latching relay so that the button now acts as a kill-switch for the ignition. All the time you hold the button down, the ignition is off.

4. Pressing the button again latches the relay back the other way and the button goes back to its starting mode, cranking the engine again.

I designed the circuit, checked, double checked everything, pulled the dash out (had to remove my old immobiliser from behind the dash), spent about 30 minutes recovering after I accidentally shut my own finger in the car's door frame, got severe back ache, and at around 9PM last night I realised my fancy system that I'd thought through in such depth just wasn't going to work.

The alarm doesn't work in the way it would appear from the instruction manual's circuit diagram. The diagram appears to show (although it is quite broken english) that it will immobilise the ignition when the alarm is engaged. I figured it meant that it switches off the ignition when the alarm is armed, only allowing the ignition to operate when I actually got in the car. I planned to use this part of the circuit to cut out and re-engage both the ignition and the acc circuit, without the key being used at all.

Instead, the alarm doesn't actually immobilise the car unless the alarm is actually set off. This means that, wired the way I wanted it, the ignition would be permanently on.

So, by 2AM last night, and to ensure I'd have a working car this morning, I'd wired a manual switch to engage/disengage the ignition circuit, wiring the immobiliser portion also into the circuit.

Here's a video of it running this morning once I had daylight again:

http://www.youtube.com/watch?v=geyk1HwiSQY

It all seems fine, but it doesn't work the way I wanted it to. Having to flick an additional switch means all the additional wiring I did to make the push-button start and stop the car is pretty pointless if I have to enable it all with another switch. I'm also not entirely happy with the design of the button, I think I need to find something that looks a bit more in keeping with the early dash.

Still, it has been a fun project so far... I figure I'm now going to be working on version 2 to iron out the bugs/flaws. Hopefully I'll be able to post back here in the future with a more complete solution for anyone else looking to go down this route.

Chris.

cb944

.. and here are some photos of the work:


Basic circuit diagram of the push-button functionality. This diagram doesn't incorporate how it will be fitted in with the alarm. Note I've drawn it on the back of an envelope like all good electricians



Relays wired up ready to go into the car:



and finally, the button installed in the car:



It looks OK, but I think it sticks out a bit too far and the chrome is out of the keeping with the rest of the car, considering there isn't any chrome anywhere else to be seen!

Chris.

IMB951

Very cool! Thanks for sharing your write-up!

alan t

Too much work for me personally, but it looks sweet!!

nh7cy

Cool. Perfect for bank robberies.

A few automobile manufacturers (Suzuki for instance) have a design that disengages the tumblers on the regular ignition switch. The switch is designed so you can turn it without a key (if the RFID key is present) thus disengaging the steering interlock, or you can use a regular non-RFID key if the RFID key is somehow lost.

944Ross

I hope you aren't using Bosch relays!

Can you make it so the Start button isn't illuminated all the time?

cb944

Thanks for the comments! When I've ironed out the bugs, I'll try to put together a more complete write-up with more information about the 944's wiring. I suddenly realised I really needed a lot more information to make this thread really useful, but I didn't get the right photos at the time.

lol, no Bosch relays in sight! The next circuit I'm going to make will probably put the light on when the ignition engages (eg, when you get in the car), then switch the light off when the starter's been engaged. I'm not sure yet though, I'm trying to work out what would be best, but it's certainly a bit too bright when driving at night.

nh7cy - I think I've seen a Suzuki with the ignition method you mentioned. It's a more discreet solution, but I sort of think an actual engine start button looks a bit cooler

It's funny how these things spiral out of control, I only started this project because my original immobiliser needed to be replaced!

F18Rep

Ha, newbies... I can top that. I have whole car projects that are like this. Heck I have a 911 that I have to drain the oil or get flooded out of the garage. You think your start button is bad, imagine everytime you need to run to the store - first have to add seven quarts. My driveway is asphalt now, it was gravel last year....;]

I knew a guy once that bought a new Toyota. Took the day off of work to change the oil. Wrench slipped against the starter terminal, welded itself there, turned bright red, ignited the dripping oil, burned down the house. You have far to go, Grasshoppah.... Bruce

M758

My race car has a push button starter.

It was cheaper and easier that replacing the bad ignition switch.

cb944

LOL!

I can believe it... the funny thing is, I've had this 944 maybe five years, and I've just driven it. Not much in the way of problems, two driveshafts and an oil cooler gasket. That's it. I guess I just got bored and in the last six months I've started pulling all sorts of things apart. I think it all started when I was 20 and I bought a Peugeot 305, pulled the windows out, pulled the lights, grille, mirrors, etc, rubbed the paint down and figured I could respray it a different colour in a weekend, removing some serious rust at the same time. It took me two weeks.

I have never, ever, ever, learnt my lesson. I thought I could pull the dash in this 944 in a weekend. You have no idea how much weird and random wiring I pulled out. Anyone need some sort of early 90's amplifier?

And yes, I definitely still have much to learn

cb944

OK.. Here's a continuation post.

So, this is sort of moving a bit further out of the realms of a simple push-button start project as the title suggest, but really I only wanted to have this if it was actually going to be useful to me... which basically means I'm trying to be as lazy as possible as I can't even be bothered anymore to get my keys out of my pocket for a simple thing as getting into a car, or starting it up

I figured out with the alarm I have here that I have no continuous +12V signal from the alarm to tell me if the alarm has been armed or disarmed. I only have momentary signals. This kinda ruled out my original intention of wiring the alarm directly into the back of the ignition switch to switch everything on or off when I get in/out of the car. For a while I thought I was screwed but then I started looking for alternatives.

So, I went back over the alarm circuit diagrams and realised I could probably connect into the central locking circuit on the alarm. Here's what it does; the alarm sends a +12V signal momentarily down one wire when the doors are locked. It sends another +12V signal down another wire when the doors are unlocked. This is only a momentary pulse, so I can't use it straight off to switch everything on, as it'll only be on for a second. What I did was wire a relay up with a feedback on the 'ON' state so that when the relay is momentarily engaged by the central locking, +12V goes back through the relay and onto the coil, so it then stays switched on, even with only a +12V pulse:



Obviously, the problem then is that the ignition goes on and stays on - how to I turn it off? I need to momentarily break the wire feeding back onto the relay coil. Fortunately, I can use the alarm's OFF signal for this. The alarm needs to be wired up so that the central locking system has 12V available to it (on the COM connection in the diagram. NC stands for 'Normally Closed', NO means 'Normally Open'). This means I can run the relay's 12V through the NC and COM connection to complete that 'feedback'. The NC and COM will normally be connected, except momentarily when the alarm tries to lock the doors, at which time it'll disconnect the relay and switch everything off!

Apologies for the crossed out bits on the revised diagram:

[DIAGRAM] agh, I'm missing this diagram.. I'll add it soon, I think it must be on my phone!

So, now wiring it up into the car. Here is my relay while testing:



Below is the plug on the back of the ignition switch. The important connections are the wire in the middle of the plug - this is your 12V coming in. You then have two other wires, one at the bottom (yellow and black) which completes the ignition circuit, and the smaller pin at the 3 o'clock position (forget the colour, think it was blue?) which switches the ACC on. There are also some black earth connections on one of the other pins that I used while wiring up the relay, but I had some weird relay switching effects going in some configurations, so I think I probably should have just wired in my own earth.



You may also notice on my circuit diagram that I've included some wiring for the lighting circuit. If I switch the lights on, I want them to automatically switch off when I get out of the car. I can do this by overriding the +12V feed to the light switch, using my 12V signal feed from the relay I now have which switches on when I move towards the car. Here is the back of the light switch, with the pin numbers on it:



This is a fairly straightforward switch. Helpfully, the '58L' and '58R' pins are actually the left and right front/back sidelights, which might be useful for something. '58' appears to short across '58L' and '58R', I suppose to provide 12V to the lights when you flick the sidelights on. Pin no. 30 actually provides all the power, so I cut this wire and replaced it with a wire from the relay. This pin also seems to be responsible for supplying power to the instrument cluster lights, so it's pretty handy for me as I wanted them to switch off as well.

This switches the lights off, but doesn't make them go down. To do that, I think pin 30B (probably worth checking that, my memory is a bit off!) gets 12V when the switch is in the OFF position. Therefore, I can now provide 30B with 12V from the new relay so when the ignition goes off, the lights will also switch off (if they are on) and the headlights will go down. Unfortunately, I found that connecting this up directly was causing weird issues with the new relay where it would continually bounce on and off while the lights were shutting (although it did function correctly), therefore in the diagram above I've planned to put an extra relay into the circuit to prevent this from happening. I haven't got this far yet though as the company I ordered my relays through sent me one relay and a TV aerial cable instead of two relays, and I'd only bought these as spares!

I also found that there was a blown bulb behind the light switch, so I replaced this and now the light switch lights up at night. I never knew it was supposed to do that, so if you have an old dash 944/924 and you're looking to fix something simple that will make you feel better, you can actually pop that switch out without removing anything else and chuck a new bulb in there

I further also wired the indicators up to flash when the alarm arms or disarms - this was fairly straightforward. I found that under the plug on the back of the indicator stalk (the rightmost plug on the stalks in the photo below), the stalk pinouts are actually labelled and there is an 'L' and an 'R' pin. Putting 12V on these pins makes the indicators permanently switch on, so I could take the indicator flash feed from the alarm and connect it into these points:



That about covers it so far. I also wired in the siren but I don't have any photos of that.

So, basically, now when I walk up to the car's door with the alarm's keyfob in my pocket, the alarm disarms, which switches the ignition and ACC circuit on. If I left my lights on when I got out of my car, the lights will also come back on. When I get out of the car, the ignition will switch off, all accessories will switch off and all lights will switch off.

The only functionality I seem to have lost is the indicator setting which originally let me able to leave either the left or right sidelights on when the ignition is off and the indicator is set either to the left or right. I'm not sure where the problem is there so far, but I have a couple of ideas so hopefully it'll be fixable.

Chris.

AKCJ

Very cool stuff, thanks for posting.

I always thought it would be cool to use my remote start (not a porsche) and skip using the key. It would require disabling the brake kill switch (and probably other circuits). The remote start is very common here due to the cold weather.

. . . just thinking further, it would be bad to have to dig the remote start out of your pocket to shut off the engine. Maybe install a kill switch on the dash. . . .

For anyone interested there's a cool web site called 12voltguy.com for switches and stuff.

Mike C.

You have some good ideas...

MN

Instead of a physical push button start, what about a virtual push button start, e.g. as an iPhone/iPod app?

As far as I know, right now only VIPER SMARTSTART (www.viper.com/SmartStart/iPhone/) offers virtual push button (as part of a "remote start" feature) but also requires an annual service plan since it uses cellular services for that feature.

A virtual push button start via Bluetooth and/or the iPhone dock connector, therefore not requiring a cellular receiver/transmitter in the car; ... any iPhone app programmer on Rennlist?

MN

cb944

That would be cool. I was actually thinking about this as a possibility while working out my push-button start/alarm project... I'm a computer programmer by trade and I thought it would be pretty neat to code something for my phone. With a Bluetooth data connection, you could pretty much control anything and log all your instrumentation data at the same time. Plus, if you mounted the dock cleverly, you'd have a complete media center and sat nav as well.

There were a couple of things that put me off going down that route.

1. It would be a long term project to create such a complete app. OK, the initial version with just a push button start and maybe an extra screen of info wouldn't be too hard to complete, but I can see it becoming quite a major development project quite quickly... not that that usually puts me off, but this wiring I've done so far has been complex enough for what is supposed to be a weekend project!

2. The main problem is that you need a bluetooth/dock connection to something within the car. Short of building your own hardware device, you're going to need a computer inside the car with all the issues of boot time, software to load and the inevitable bugs and crashes. It also means it's not a complete solution because you still ned your keys or an alarm to lock/unlock the car, then you have to get your phone out, put it on your dash and remember to take it with you along with your keys when you get back out of the car.

For my money, I think the best way to go will be to wait for something like the Archos tablet running Android 3.0. If a hardware interface could be built to allow it to switch stuff on/off and record data from sensors, then a front-end could be coded to operate everything within the car and the device could be switched on/off by using a passive entry alarm system such as the one I've got.