Wiring satellite navigation into an Mazda MX5
Question:
I am seeking to hard-wire a sat-nav device to my Mazda MX5 (2007). I am reasonably experienced in electrical matters, and I note that the sat-nav is powered at 5 volts. I also note that most sensors in engine management are also powered at 5 volts.
Do ECU’s have a 5 volt bus that might supply the extra 1 amp that a sat nav demands?
I’m trying to avoid the trailing wires and bulky step-down cigar-lighter plug that most sat-navs use.
Sorry to land this on your desk, but I can’t find local experts willing or able to answer this.
Answer:
The short answer, I’d say take it to your Mazda dealership and talk to a mechanic. They’ll help you with the right splice and 5v wire to use.
The longer answer (if you want to do it yourself) would consist of an electrical schematic for your car (like a Haynes car repair manual, or if you’re lucky, the manual that came with your car). You’ll have to research or experiment to find the correct 5v cable. I’m not sure exactly what component you’d like to feed power from when you reference the ECU, but one common application I’ve seen is to splice a wire to existing wires for the radio or dash lights (or other cable with the right power requirements). Another is to get a special plug adapter that let’s you plug your device right into your fuse box, giving you your choice of voltage and amerage (I’ve never used these, I’ve only heard about them, so don’t take my word that it works properly).
I’m leery of splicing onto a car sensor like you mention (I assume you mean things like the temperature sensor, o2, et cetera?). I wouldn’t want to affect the performance of a part that could hurt my car’s performance or mileage. However, I’m a weekend mechanic, and not a car buff. If you’re comfortable at that level, go for it.
