Dial a car to start up its engine

remote-car-starter.jpgI’m a car starter. A cellphone car starter...’ With a mobile phone-based car-starting device we are continuing a theme here – back in January we highlighted the work of Gadget Master Alvaro, who wanted to take control of his gadgets, via an SMS Remote Controller. See Taking texting control of your gadgets. Thanks to Engadget for highlighting this $10 DIY device made by Dave, as a possible alternative much more expensive car-starter systems, like Viper. It’s interesting, but falls into the ‘Don’t Try This At Home‘ category! The website writes:

This hack from a guy named Dave…[relies] on a cheap prepaid cellphone that has had its vibration motor surgically removed, replaced by a couple of leads triggering the car’s starter. Now, whenever the phone receives a call it starts up the car — a somewhat dodgy proposition if a telemarketer ever gets hold of your number, but an interesting solution nonetheless.

Check out pics, a diagram and project info on his Dave Hacks blog. car-starter.jpg He writes:

The remote start requires 2 pulses within 3? seconds to initiate the remote start sequence.  So how to send those 2 pulses?  Easy, I remove the vibrate motor from a cell phone or pager and use that circuit to initiate the remote start by setting the phone to vibrate.  But wait – the RSAI only works when put to ground, that circuit has (after testing) a 1.35v current. I guess I have to use a relay!  Oh no… The remote start turns off after 2 MORE pulses.  How do I get the cell phone to STOP sending rings?  Hrm…

Apparently, the device could be extended, with the aid of timers and alarms on the handset to auto-start the car at pre-set intervals… Hmmm. Not so sure about that. Does anyone else believe that just idling the enginge helps ‘warm’ a car up? One puzzle, for me, is how the relay works on the phone’s low voltage. Also, wouldn’t a proper solid state relay be a better choice than overdriving an opto isolator well beyond its maximum ratings? What do you think?



  1. You are right, David, that is quite confusing, but we can guess what he means.
    Pushing 420mA through a 20mA opto-isolator seems a little cruel!

  2. Not too much of a problem for the original poster. They’re American, and therefore are likely to have an automatic gearbox. Also, the automatic/remote start mechanisms that are fitted to US cars generally won’t start the car unless the gearstick is in the “Park” position.
    However, I am wondering what a “1.35v current” is…

  3. Yes, and what happens if you (as I always do) leave the car in gear? Wonderful.

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