I have an '04 Mazda 3i

I asked a mechanic to wire a radar detector which would turn on with the ignition key. He said he could not, because the Mazda does not have a key-switched circuit breaker in the fuse box. All the breaker circuits are always on. He could cut a wire in the wiring harness, but that would void my warranty if I had problems there.

He wired it into one of the fuse box circuits. It is always on unless we manually turn it off. If my wife or I forget to turn it off, it squawks a lot while it is sitting, even in the garage or when we aren't around. When I went on a trip for three weeks, it ran the battery down and I had to get a jump (not easy or cheap in O'Hare).

Does anyone know how to tap into the keyed circuit without cutting a wire or disturbing the harness?

 

Why not just splice into the radio circuit ???

 

A friend knows a mechanic in a Mazda dealer. I talked to the mechanic and he said the warranty would still be honored if the wires are spliced correctly. The best place to do it is at the fuse box on the firewall in the engine compartment. He said to just splice into any connection which is live when the key is on and dead when the key is off.