Remote start

**Ascension** · 06-22-2005, 10:38 AM

Okai, to make a push button remote start, where when the button is pushed the car is being cranked is pretty easy. And when the car turns over you just release the button.

I can make a delayed circuit, so that when you push the button it keeps cranking the car for X amount of time. But this wont work because the car would need different cranking times depending on the situation. And it could easily over crank the car and youll be with a nice new extra large paper weight.

My question is, how do remote ignition systems know when the car has turned over so that it can stop cranking the car?

**MatrixPC** · 06-22-2005, 12:10 PM

Either by voltage (14V+) or Tach signal (AC).

**DaRacerz** · 06-22-2005, 09:53 PM

Ya, what Matrix said. Often times you pre-program your remote start tach signal (since every car is different) and when that programmed voltage is reached the device stops cranking.

**Bugbyte** · 06-22-2005, 11:06 PM

My wife's car remote start has two sensors. One for voltage. If the car doesn't start, it will try again. The other is for tachometer sensing, although we don't use it.

**xdjxklusivex** · 06-22-2005, 11:38 PM

remote start is pimp **** but i wouldnt try to do it on my own id pay someone to do it lol

**Bugbyte** · 06-22-2005, 11:50 PM

It wasn't too hard. I bought the cable harness that plugs between the ignition and the car system. After that it was pretty straightforward stuff.

**MatrixPC** · 06-23-2005, 12:48 AM

I did myself on the stickshift almost 8 years ago cuz the shop refused to do it (liability reason). Not so hard. The hard part is finding the correct wires on your car. It's much easier to get the all-in-one system instead of the add-on. With add on, you have to do more wiring. All system I put on (4 totals, 2 to Toyota and 2 to Honda) are from DEI (Viper/vallet) and all have either Voltage sensing or Tach. I used tach.

**Ascension** · 06-23-2005, 08:01 AM

Okai so i take it that the alternator only starts running when the car has turned over?

So how does this sound?
When i push the button, it closes the circuit on the wires coming out of ignition barrel which will start the car cranking. And it will also be hooked up to the BAT, so when the car turns over, the 12V bat line will become 14.4 and the circuit will detect its above a certaing voltage (ie 13V) and then the circuit will open up stoping the crank. This sound right?

The reason why i want to do this is because my car takes a bit to warm up, and i cant switch over to gas till my car is warmed up.
So in the mornings when i go to school, instead of sitting in the car freezing my *** off for 5 mins, i can be inside getting ready while my car is warming up. Then when i get to my car its all warmed up and all i have to do is switch it over to gas and drive off.

**SickVette** · 06-23-2005, 09:09 AM

Switch it over to gas? Is your car a hybrid and if so which one?

Sounds like your idea will work. I guess your circuit is going to control relay for the high current section? Is the circuit going to have a learn function for the tach? On a remote starter the system learns the tach so it knows the car is running. Not all car's tach work the same also don't always tie into the tach wire...a fuel injector wire can be used.

**Ascension** · 06-23-2005, 12:11 PM

nooo... noo hybrid. My car runs on petrol/gas. Dont all cars run on petrol?
1 litre of petrol here in Australia cost like $1, prices are outrageous at the moment, where gas is around 38cents.
You get a gas tank installed and the right engine mods done, and you can now run your car on gas, much much cheaper. When i brought my car, just a cheap second hand one, i found a car that was already converted to gas so it cost me bout 20 dollars a week to run instead of 60.... car must be started on petrol till warmed up then switched to gas, dont want to waste money on petrol driving around so i leave the car in my driveway warming up.. hence the remote start idea comes into play, and now back to the point....

Now im still all new to this and have no idea what the tach or fuel injector wire is, so if someone would like to explain that to me, that would be great.

Now from what i understand, it seems pretty simple to do (but i may be missing something). if you bridge the right wires coming out of the ignition barell (acc and ignition i think) then you connect the two wires that are bridged when you turn the key to crank, this simulates putting your key in and starting the car (also i guess its just hot wiring you car) none of these are high current wires are they, just signal wires like acc?

I already have someone who is going to show me how to "hotwire" my car so i can put in a push button start.

Anyways, all i do is work out how to create a circuit that when it sees 13+ volts it triggers a relay or inverter, which cuts the line which is giving the signal to crank the car.

The only wires you need for this are the ones coming out of the ignition barell and one wire thats hooked up to the bat that changes from 12V when the car is off to 14 when the car turns over (so im guessing the acc line can be used for this)

All you have to do now, is get a remote control circuit going that you could buy some cheap kit from jaycar. But i already have one from my keyless entry.

I dont see why you need this tach wire (i dont even know what it is yet but)