I'm about to take an automotive electronics class at college but I'm just curious, what are the basics? Say I want to wire a police scanner or some type of lightbar into my car's electrical system. What would this entail? I'd have to pull away body panels, run wire, and hook it into the battery? What about fuses, safeties, etc And also how could I hook my police scanner into my speaker's system?
Fuse blocks in cars often have SPARE (usually disused in some particular model) positions with wires already attached and within the wiring loom, with nothing connected to the end. Knowing what the intended accessory was, might allow you to connect something to its unconnected end, and always, the negative return is the car's frame. The circuit must be capable of carrying the current required. Some of these spares may be connected via the ignition switch, some may not. The next alternative is to run a new wire with a fuse inline, at the supply end at least. It is good practice to fuse the supply end, then have a further fuse at the accessory end (most accessories will already have this). The wire can often be run along and fixed to the existing car looms, passing through the firewall where the loom passes through. Again, negative is anywhere convenient on the car's metal frame. A quick and simple connection is the cigarette lighter, if fitted. Just procure a plug to replace the lighter. It can supply a fair current. So far as connecting a scanner to the existing speakers, I suggest you don't try to, unless the audio/ radio system has an accessory input. Maybe a bluetooth connection might be used, but really, the scanner's own speaker should supply the scanner sound. You can also connect accessories by splicing into existing car circuits, but I would suggest you do your college course first! You really need to understand current and wire sizes and fusing (not to mention basic circuitry!), before splicing into existing wires.
