After several series of bench tests, I was finally ready to make the plunge and install my home made autostart into my truck. The vehicle in question is a 1993 GMC K3500 pickup truck. It took about 30 minutes to remove the lower dash portion and properly identify the wires in question. Then, about 15 minutes later, the whole thing was hooked up.

Then came the scary moment of truth.

I opened my app on my phone, and pressed the big orange start button.

The first set of relays engaged, turning on ignition power, fuel pump power, etc. So far so good. After the 5 second delay (purposefully programmed to allow the priming of the fuel) the second set of relays kicked in, the vehicle cranked, and STARTED!

To God be the glory! Wow! I can’t believe it actually worked! Lo and behold, pushing the stop button on my app killed the truck too! Great! By the way, the entire project, all files, apps, sketches, pictures, etc., can be downloaded from the repository I made for this on GitLab.

A few tests showed that I still have some fine tuning to do. As can be seen from the two issues I opened on the repository, there are two enhancements that really would make this better. The first is that the range is limited to about 30 feet, on a good day with nothing between you and the truck. The second is a slight problem with voltage detection for determining if the vehicle is started.

You see, I am using a voltage divider to break down the 12+ vdc to less than 3 vdc for the BlueFruit board. If it is less than 0.9 volts on the board (13 volts on the vehicle), then the alternator is not charging and the vehicle must not be running. This causes a few problems.

  1. If the vehicle’s alternator ever fails, the autostart will attempt to start a running truck numerous times.
  2. During the cranking process, the board keeps checking voltage to see if the engine started, but it will always read low when a huge load like the starter is engaged. So it will always crank the full 3 seconds of crank time, even if the vehicle is started.

Both of these conditions will cause excessive wear on the starter, and in general is just poor design. So I’ll be thinking on a way to make that better. In any event, I’m really glad that the initial run was a success!

Linux – keep it simple.

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