This is my first indestructible, I wouldn't have posted this because I always do things like this and I lose site that sometimes they can be cool or useful to others, but a coworker told me I should, so here I am. Also I underestimated the current draw and capabilities of the original design and had to correct it. This gave me the opportunity to take pictures and such for illustration. Before I get started let me say that while this indestructible will tell you how to start your car with a flash drive; this will be a reengineered flash drive and should never be plugged back into a computer or plug an un-engineered one into the car for fear of what might happen. The reason for this indestructible is quite simply I am cheap (new part is $100 and labor is $200) and I love creatively fixing things around the house with junk I have laying about. So the problem is the ignition stopped turning in my car, a '96 BMW 328i (this makes the problem more complex later). I will cover the unique challenges my car represented but also instruct the general techniques needed to adapt this for any vehicle. A side from the three automotive relays (purchased to solve the current draw issue) everything used was found lying around in my junk bins.
My parts list is:
1x Front panel USB plug from an old computer case
1x Old 2GB USB SanDisk Cruzer flash drive (who uses 2GB flash drives these days anyways)
2x automotive relays with two normal open contacts
1x automotive relay with one normal open and one normal closed contact
1x 12v relay with one normal open and one normal closed contact for electronics (had it laying around but could have used another automotive one as well)
Step 1: Remove the vehicles interior panels
The first step is to remove the interior panels in the car to gain access to the wire harness used for the ignition. This varies for every vehicle and is outside the scope of this indestructible. While you are removing the panels take note and plan where you are going to mount your USB plug. I chose to mount it on the lower panel that covers the steering column. Keep in mind that your wire length will also be a limiting factor in your placement. Carefully measure and cut a hole where you wish to mount the plug, keep in mind there needs to be clearance from other parts in the vehicle when you reinstall the panels. You may want to double check multiple times to ensure you have chosen the right placement. A wrong choice will lead to multiple holes in your interior panels which never looks good.
By the way, the interior plastic is very tough to cut so if you chose to do it by hand as I did please be extremely careful not to cut yourself. I used a hobby knife to carefully cut the hole in the plastic, but what you have or choose to use is up to you. I thought about using a Dremel but chose to do it by hand so I had more control and provide a more accurate result.