Remote Kill Switch for a Car

Most cars stolen in America are taken when the thief has the owner's keys. This system prevents car thefts without sacrificing convenience for cars with remote start. It is plug-and-play for most cars and can be assembled in less than an hour.

Car starter relay (could be different depending on make/model. Make sure to do your research and find one that works for your car):

https://www.oreillyauto.com/detail/c/bosch/bosch-30-amp-4-terminal-relay/bos0/0986ah0115?q=4+pin+car+relay

12v remote-controlled switch:

https://www.aliexpress.us/item/3256805986453416.html?spm=a2g0o.productlist.main.15.4c723eb85HVURH&algo_pvid=232bd2ec-3a6c-48ff-99ec-af29a0b74d65&algo_exp_id=232bd2ec-3a6c-48ff-99ec-af29a0b74d65-14&pdp_ext_f=%7B%22order%22%3A%223060%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21USD%215.79%210.99%21%21%215.79%210.99%21%402103128817792091731866499e6e1f%2112000036120260220%21sea%21US%210%21ABX%211%210%21n_tag%3A-29910%3Bd%3A351bc82f%3Bm03_new_user%3A-29895%3BpisId%3A5000000203537378&curPageLogUid=qSE673hlVsTc&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A1005006172768168%7C_p_origin_prod%3A

20-gauge wire:

https://www.homedepot.com/p/Southwire-100-ft-20-2-Twisted-CU-Bell-Wire-56750023/205717549?source=shoppingads&locale=en-US&fp=ggl&srsltid=AfmBOopqBO1JuiXWNHEOPk6jpTqPtoGffkvMMLYJfFIyOV87nT0Jxp4PnYw

14-gauge wire:

https://www.amazon.com/VIABRICO-Electrical-Conductors-Lighting-Extension/dp/B0CKQ2172Z/ref=sr_1_6?dib=eyJ2IjoiMSJ9.8R5hMeo85q-c_e-IB0N6OdwMhioM5Tx6XNJE1867OHjoe6iUtiPQPxf2K4wHKnk1FiBr1Ro2kO0TJjkndq21H4-vHg2Ku5rAlKOYFM_USIEmNY0AtDFwSo_7E1c9OsPHFfWZV-0k91PHBOWj9SOnAi5RoJc_uO3tPgCrf3gJbDv84eCH27pL5LK5ugAVawHqTFtYK01ZGMaQcWJe6YPbMU_1-dNirqOjiryoMifAAPIK0akcM-rOMIaFyiDrO1WB9ndzMYDm__0VF1ls3quIObHyAUTCDP_aetP6CaLIMpU.In29zITkM5fQ39iU3TiIXzJ6LQTvd_dyzYhUw-s0bPg&dib_tag=se&keywords=14%2Bgauge%2Bwire&qid=1779209501&sr=8-6&th=1

Connector for battery:

https://www.amazon.com/TKDMR-Battery-Terminals-Connectors-Assortment/dp/B09XGQN2NS/ref=sr_1_2_sspa?dib=eyJ2IjoiMSJ9.b8j5ceBO_btk463O17SFtgSZjDK3j4FEl5X_Fn1x_duzjp1HXz03iOYeWUQy5N1PMldFZ9CN_YRmmMB3-XQ7uUwN5CYpEKJ9_P60qAJhJastSGAGBuSAoroUhAao7C7jbe6bx3C5aPBPqF3lMdMWJCaegfq9WhRA29uHI6k4jpvV2JUSxuJjL5apmMnoXO72YJ-YlUKyJTccHk1qnjo4JPt9GpjPQ-z27O8rQolUYZQ.50KOEi2Bj1NzH1w0ZDrelK_qQWp0yextUQiCefCn1SM&dib_tag=se&keywords=battery%2Bterminal%2Bconnectors&qid=1779209909&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

2-position switch (optional):

https://www.aliexpress.us/item/3256808609390012.html?spm=a2g0o.productlist.main.2.54664a8chpUYaT&algo_pvid=be56191f-3e91-482c-8a07-3cba813c22a5&algo_exp_id=be56191f-3e91-482c-8a07-3cba813c22a5-1&pdp_ext_f=%7B%22order%22%3A%22382%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21USD%213.02%210.99%21%21%213.02%210.99%21%402103126e17792101430604520e4e78%2112000046698882430%21sea%21US%210%21ABX%211%210%21n_tag%3A-29910%3Bd%3A351bc82f%3Bm03_new_user%3A-29895%3BpisId%3A5000000203712600&curPageLogUid=sAp943fgphLJ&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A1005008795704764%7C_p_origin_prod%3A

Threaded Heat Set Inserts, m4 (optional):

https://www.amazon.com/initeq-M4-0-7-Threaded-Inserts-Printing/dp/B07473ZV71

1: all supplies above

2: wire cutters

3: soldering iron + solder

4: Philips head screwdriver (small)

5: flathead screwdriver (or other pry tool)

5: electrical tape/heat shrink

6: 3d printer (optional)

Use the pry tool to slowly pry off the outer casing. The case is usually just a plastic shell on top of the components and the bottom plug area. If you separate the top shell from the bottom plug area, you can access the wiring inside.

In the starter relay, there is a solenoid that connects to two of the terminals (shown above). Disconnect the wire connecting the solenoid to the negative terminal. You can usually do this by heating the solder on the metal casing and connecting the wire to the terminal. If you heat the point with the soldering iron for a few seconds, the wire should come loose. At this point, you have to solder in two 20-gauge wires, one to the wire you just disconnected, and the other to the metal casing it was attached to. Once done, prevent a short circuit by adding heat shrink or electrical tape. Place the casing back on the modified relay (if necessary, remove material from the casing).

Feed the relay wires into the on and off stations on the board. Then connect 2 14-gauge wires to the input and output terminals (these wires must reach the battery terminals at the other side of the hood, so make sure they are sufficiently long - at least 5 ft). Once connected, add the battery terminal connector ends to the 14-gauge wires. Connect the system to power, then follow the instructions on the remote switch board to pair it to the remote (this step can be done while the twitch is connected to the battery if you do not have a power supply). Once paired, the system is ready.

Unscrew the remote, and place the remote controller board into the new casing. If you want to make a custom casing for the remote controller, a 3D-printable negative is provided below. Create your own design, then insert the file as a hole into your design. You also still need to print the cover for the casing provided below. If you are using the negative to make your own key fob design, you will need to use the m4 heat-set inserts listed above to make a screw hole.

Turn your car fully off. Disconnect the battery's contacts, and wait for 20 minutes (negative terminal first, then positive). Replace the starter relay in your car with the starter relay connected to your circuit. If the relay doesn't fit right or is a different shape than the OEM one, don't put it in. Find the correct relay. The incorrect one could prevent your car from starting. Make sure the relay is positioned correctly, then connect the battery connector terminals to the connectors on the 14-gauge wires. Reconnect the terminals to the car (positive to negative). Wait 5 minutes, then switch the switch to the on mode, allowing power to flow through the relay, and start the car. Remember that all cars look different, so be sure to look up your specific make and model to find the correct placements for everything. Congratulations, you have done it.