i wired in a brake light kill switch over the weekend in my car seeing as how i regularly encounter rear laser in my area and my brake lights would certainly tell the tale on me if i used them to slow down when jamming.
i decided to use the fuse as a point where i could break the circuit without harming any wiring in the car. that and i wouldnt have a clue how to find it anyway ops:
at a local auto stores, i got an illuminated rocker switch, an in line fuse holder, some 15amp fuses, a few male and female spade connectors and some 17 amp wire (brake lights are 15 amp fused but the wire has to be able for more or it would be pointless).
i removed the original fuse from the fusebox and replaced it with a few connectors i made from fuse blades soldered to the 17 amp wire and the in line fuse holder with a 15 amp fuse is on that line also. this went on the live point in the fuse box and to the "power" connector on the switch using a female spade connector.
i then ran the other length of wire from the other side of the fuse insert point and crimped another female spade connector to that and connected that to the "accessory" point on the switch
the third connector on the switch is the "ground" which enables the switch to be illuminated when the accessory is switched on so i will know by this if the brake lights are functioning at a glance . i wired this to a bolt on the cars internal bodywork and that works fine too .
this is something to be used very carefully but it can be extremely valuable in a rear laser scenario, especially in an area where CMs are illegal and braking when hit by laser from behind can tip off the LEO that you knew he was hitting you :wink: .
the beauty of this installation is that it can be removed very easily and undone completely by just popping the original fuse back in place again leaving no trace