Hey all,

Just wondering if there was a way to create a simple remote start setup. I have around 10 spare relays and a spare channel on my alarm which I can use to activite it.

It does not need any safety features as the car is an automatic not manual.

Just looking for something simple so whenever I hold down the button on the remote the car will crank and eventually start and when I let go it will stop cranking.

Any one have any ideas, I've seen something on the net before about doing it but cannot seem to locate it anymore.

I know it would be easier to go out and buy a new alarm with remote start feature but I think it would be pretty cool to do a DIY job.

Anyways thats it, hopefully someone can help.

Thanks in advance

 

The short answer is no, not really.

When a remote system starts a car, there are a few stages it goes through.

First, continuous power is sent to the ignition system, so that the fuel pump, PCM, etc. are now powered. It then will pause for 1-5 seconds. More if in a diesel vehicle, to allow the glow plugs to warm up.

It also sends continuous power to your running and marker lights.

Then, it sends power to the starter to crank the engine. It will either do that for a pre-set number of seconds, or else it does it until it gets a signal of a certain strength from the tachometer, which would indicate that the motor is running. If the latter, there is also a timer for cranking, so that it will not crank forever in the event of a no start.

There is an RPM cutoff (usually around 3000) so that it won't overrev if, say the throttle is stuck

There is also a timer in the system, so that it won't run forever.

Finally, there is another shutoff wired to the brake pedal, so that when you get in, put the key in the ignition, and put your foot on the brake to shift into gear, it will turn off the remote start and go to ordinary system power.

That is how a proper start system will work. If you describe your alarm a bit more, maybe I can suggest somethings to do this in your vehicle. Some alarm manufacturers also sell add-on modules that can add the command start functionality to your existing system. I'd check that as well. Cheers,

 

yeah i realise a proper system will have much more safety features but just looking at something that will crank the starter motor and then start the engine when i hole the button down. I will only be doing this when near the vehicle and its an auto so it will not need any safety functions.

It is just a basic alarm with a spare positively triggered channel that could be used for boot release or any other function really. There are no add-on modules that would provide remote start for this alarm.

 

Then you can MAYBE do a system like this, if you're good. Here's how:

Set up the channel as a momentary pulse, so that it will pulse as long as you hold down the button.

You will need to make a system up to power the accessory system in the car AND keep it powered, even if the starter isn't cranking (button is no longer pressed).

For that, you will need to set up a relay network that will
1. Supply 12 v to the system when on
2. Will Turn on with a pulse, but then keep itself on when the pulse stops
3. Turn itself off when grounded or when a different pulse happens

For this, you will need two types of relays: 1 normally open (standard relay) and 1 normally closed (less common)

Input for the normal relay will come from the alarm. There is a diode attached between the alarm and relay

output from the relay will go into the normally closed relay, and from there to the ignition power system AND back to the input of the first relay, between the diode and the relay. This will make it self-powered, but the diode prevents power from going back up the system.

Then, you need a means of interrupt. I'd just run a signal from the brake switch to the signal input of the normally closed relay (#2) Then, when a signal hits that relay, it brakes the circuit that keeps the first relay going, and the whole system collapses.

Then you'll just need another relay to send power to the starter as long as the button is pressed.


So when you want the car started, press and hold the button.

It will energise the fuel pump and whatnot, and crank
when you release the button, the fuel pump will stay on, cranking will stop.
When you want to drive, get in, put key in and turn to "on", and press the brakes. The relay network for ignition power will collapse, but you now have ignition turned on at the key, so it will stay running and not go through the relay system you built.



That's just my half-witted guess at how you'd make one of those. Just remember, though, I'm not an engineer. Yet. That's 4 or 5 years off....

 

err...Well i know on my alarm/remote, you can assign 2 channels per button. 1 if you tap it, and another if you press and HOLD it for 1.5 seconds or whatever. Will yours work like that?

I dont know...But what if you hooked it up straight into the ignition switch itself. Just trick the car into thinking the key has been turned. 1 channel (tap) to short the 2 ignition switch wires that lead the relay under the dash so tapping the button turns the car "on" and off (this would prime the pump and put power to everything) and holding the button down would trigger another channel hooked up to the crank. Tap, then tap and hold, car starts.....And if it sounds like it's revving like mad or something, just another tap and it's off again.

Just a half-thought out idea.......