Tutorial: Build a Cellular (SMS) Remote Car Stater

How to wirelessly start your car using a text message.

Objective

Extend the range of my vehicle's auto-start using the cheapest solution I can think of. I would also like to keep vehicle modifications to a minimum (or none).

Solution

Trigger the auto-start remote using an Arduino connected to a cell service. User will send an SMS message to the device, which will validate the message then trigger a relay which will cause the remote to send a signal and the car will start. The device will be left in the car and run off the vehicle's battery.

Skills required

If you follow the tutorial, basic computer and electronics skills. I am assuming you can make connections using a bread board or soldering iron. I am also assuming your car already has a remote starter installed, and that you are willing to sacrifice one of the remotes.

Required Materials (Click to Buy):

• Arduino Uno $10
• Relay Module $5
• GPRS Shield $30
• SIM Card: Ting or T-Mobile
• Breadboard & Wires (or solder)
• Car Start Remote Control
  ** This tutorial requires your car already has a remote starter installed.**

Estimated Cost:

Materials:  $45
SIM & Service:  $10 SIM Card + $8 monthly.

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Step 1: Hack your remote starter.

I decided to go the quickest an easiest route for me (this will vary depending on your remote). I jumped the connections of both buttons, to simulate them being constantly pressed. Then connected wires to the battery terminals of the device - in short, when the relay is triggered it will supply power to the device which will immediately try to start the car. Test the remote by holding the wires to the battery it came with and see if your car starts, if it does- you're ready for the next step.

Step 2: Set up your Arduino and SIM card.

We are going to setup our Arduino to remotely control the relay with an SMS. The relay will have a light and a clicking sound when activated, so no need to hook up your remote stater to test this (unless you like turning your car on repeatedly).

First place the SIM card into your GPRS shield then attach it to your Arduino. Next, connect the Arduino to the relay.

GND to GND
5V to IN
PIN 12 to VCC

Step 3: Configure and upload software.

Downlaod the code:
https://github.com/zenvent/RemoteCarStart

This step can be copy paste, or you can modify it to do much more. My software does a couple things: It will check the phone number before accepting any commands, if it is not your phone all commands will be rejected. It will then check the command, if it exists it will be executed. The command to turn on your car is by default 'Start'. Please review the code below and modify it as desired. Open RemoteCarStart.ino and enter your mobile phone number for #define phone_number. Click verify and upload the firmware. Congratulations, you're done with this step.

Step 5: Test.

Test sending a variety of messages to the Arduino, and verify what you expect to happen is appearing in the console. If it is, you're almost done.

Step 6: Complete Connections

Hook up the battery and remote to the relay. Connect the negative lead from your battery to your remote, and connect the positive leads from the remote and battery to the relay (make sure to use the normally off pins). You're device is now ready to turn on your car! You can power the Arduino directly from your car using a Car DC USB charger, or you can connect your Arduino to a power bank, then your car for best performance.