Here is a popular kill switch selling online everywhere, but it's clearly not for every year,make and model ...because as a battery shut off, it kills All power, so anything that needs electricity to keep a memory of a clock, seat adjustment, mirror adjustment or radio stations will be blank and cleared including maybe things stored in the cars computer.. But it can be used and wired to kill something else to deter theft..
like cutting off the fuel pump, starter solenoid power wire, neutral safety switch, the possibility is endless, just have to use your knowledge of Vehicle wiring...
as for using it on an older car with no electronics, it should be good, but I would use it to kill other things that I have noted instead of the battery cable..I wouldn't trust that relay to run all the time when engaged and to hold a load for a long time...
S12E914
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   • Mustang or Similar Anti Theft Hidden ...