eli5: How hard is it to hotwire a car?


Like when you turn the key in a car, it completes a circuit right? How hard is it to just take the wire connected to the switch and touch them together?

In: Technology

Newer cars are basically impossible . Older cars such as a 1996 Honda Accord for example you can hop in and have it going in 45 seconds .

As stated, old cars it was relatively easy. Gain access to the wiring off the ignition cylinder and complete the circuit, easy-peazy.

New cars run near field authentication protocols or imbedded chips in the keys that need to match encryption in the ECU. So unless you can overcome that… there’s no hot wiring in that cars future.

Older cars are as easy as you describe. You just need to provide power to the ignition circuit and then the starter circuit. In order to do this fast though you need some knowledge of the car so that you know which wires to short circuit. Some cars do somewhat protect the wiring loom from the ignition key making it harder to find the correct wires as well.

However to combat this people started to install anti-theft systems in their cars. First it was third party systems but then these became incorporated in the cars design and are now pretty much standard. In addition to a normal key there is now electronics in the key which communicate with the car over radio to identify itself. So the electronics of the car will not allow you to start the car without the correct key in place and may even sound an alarm if you try. So it is no longer enough to just short circuit a few wires together but you need to trick the computer into thinking you have the correct key. This is still fairly easy but it means that car thiefs have to learn some basic electronics skills and some programming in order to make the tools required to hotwire modern cars. And it is expected that car manufacturers will soon start to incorporate some actual security measures like electronic signatures in these keys making it much harder to fool the computers.

It was pretty easy long ago or in older vehicles. Connect the ignition circuit, the one that completes the circuit for the coil/battery/alternator, and then connect the starter circuit that feeds power to the starter motor that initiates the system to those wires and it would start and run. [Three wires](https://i0.wp.com/i.kinja-img.com/gawker-media/image/upload/s–pEKnRGXX–/c_fit,fl_progressive,q_80,w_636/18n268n6mpbljjpg.jpg).

Today’s vehicles are much more complex and hot wiring one involves bypassing and/or feeding power to a lot more systems, some that are computer controlled and need an electronic signal from a computer chip in the circuit to work. Starting these involves completing a lot more than just the ‘run’ and ‘start’ circuits. Extremely difficult in most cases.

If you get a very old car, you just look under the back of the panel from where you put the key in, see the few wires coming off the back of it, and make the right connection between them to enable ignition, then temporarily engage the starter by making another connection.