iceman
07-08-2003, 11:43 PM
This is meant to help new installers get their feet wet in doing their own wiring work in their car, as far as adding extra accessories go... Please, I'm sure I'll post some bad info, or won't say things the best way, so if you have something, ADD ON !!!!
Always disconnect the negative battery terminal when working on your electrical system! Working on live electrical system = bad.
When you take a step back.. just about every wiring job in the car ultimately comes down to the connection of 2 wires to your accessory- positive, and negative AKA ground.
Basic Stuff
Most people can follow instructions for hardwiring accessories, but have trouble figuring out where to make the positive (+12V) connections. Negative is easy in our cars, because the cars electrical system is whats called a negative ground system, which means that the entire chassis, anywhere there is metal that is part of the frame, is a ground.
First, figure out when you want your accessory to have power. You have 3 choices..
Constant Power - Will always have power, as long as the battery is connected.
Accessory Switched (ACC) - Will have power when they key is in the ACC position (or anything past it besides start)
Ignition Switched (IGN) - power only when the key is in the ON position
Determine when you want your accessory to have power. Common uses for constant power are underbody neons, accent lights, horns, fan overrides, etc. Common uses for ACC power are things you would use when the ignition is off, but not constant - the radio operates on ACC power. Common uses for IGN controlled circuits are radar detectors, high current items like fog lights, and other things you would only use when the car is on. Stock IGN powered items are wipers, sunroof, etc.
Once you pick your power source, it's time to find the actual wire where you will be getting your power source. One of the easiest ways to do get power signals in a car is to tap an existing fuse. Most people will just jam a wire into a fuse and shove the fuse back in, holding the wire in place. While this will work, it's not the best way, but I'll still offer some help if you choose to do so.
- Use an aftermarket "add a circuit" fuse tap from an auto parts store. This inserts into your stock fuse plug and provides an outlet for the stock fuse (original circuit) but also provides a second fuse spot, and lead, for your new circuit. This is goo because it does not interfere with the original stock circuit.
-If you are going to just jam a wire in the fuse, or use a fuse tap, it does matter what side of the fuse you tap. Look at your fuse panel map, and you'll see each fuses' current rating, and a little + sign on each fuse. Tap the side without the +. The + signifies that that is the input power for that fuse. If whatever you add ever shorts out, at least you will pop the fuse, and not torch the wire thats connected.
Easy places to get power
ACC: Any fuse marked ACC
IGN: Any fuse marked IGN, sunroof, wipers, turn signals, windows
Constant: Anything marked BATT, the battery itself, and the secondary battery terminal (under hood fuseblock)
If you choose to tap a fuse, you don't want to put high current accessories on those taps. You will want to make use of relays (see below). For example, don't put 10 neon lights on your sunroof fuse and wonder why every time you open the sunroof when the neons are on, the fuse blows. Things like gauges, radar detectors, small things etc, are generally ok piggybacked on top of a stock circuit. Especially one that isn't always on, like the sunroof, windows, blinkers. When you have multiple things to power, or high current items, use your fuse tap to power a relay.
Always disconnect the negative battery terminal when working on your electrical system! Working on live electrical system = bad.
When you take a step back.. just about every wiring job in the car ultimately comes down to the connection of 2 wires to your accessory- positive, and negative AKA ground.
Basic Stuff
Most people can follow instructions for hardwiring accessories, but have trouble figuring out where to make the positive (+12V) connections. Negative is easy in our cars, because the cars electrical system is whats called a negative ground system, which means that the entire chassis, anywhere there is metal that is part of the frame, is a ground.
First, figure out when you want your accessory to have power. You have 3 choices..
Constant Power - Will always have power, as long as the battery is connected.
Accessory Switched (ACC) - Will have power when they key is in the ACC position (or anything past it besides start)
Ignition Switched (IGN) - power only when the key is in the ON position
Determine when you want your accessory to have power. Common uses for constant power are underbody neons, accent lights, horns, fan overrides, etc. Common uses for ACC power are things you would use when the ignition is off, but not constant - the radio operates on ACC power. Common uses for IGN controlled circuits are radar detectors, high current items like fog lights, and other things you would only use when the car is on. Stock IGN powered items are wipers, sunroof, etc.
Once you pick your power source, it's time to find the actual wire where you will be getting your power source. One of the easiest ways to do get power signals in a car is to tap an existing fuse. Most people will just jam a wire into a fuse and shove the fuse back in, holding the wire in place. While this will work, it's not the best way, but I'll still offer some help if you choose to do so.
- Use an aftermarket "add a circuit" fuse tap from an auto parts store. This inserts into your stock fuse plug and provides an outlet for the stock fuse (original circuit) but also provides a second fuse spot, and lead, for your new circuit. This is goo because it does not interfere with the original stock circuit.
-If you are going to just jam a wire in the fuse, or use a fuse tap, it does matter what side of the fuse you tap. Look at your fuse panel map, and you'll see each fuses' current rating, and a little + sign on each fuse. Tap the side without the +. The + signifies that that is the input power for that fuse. If whatever you add ever shorts out, at least you will pop the fuse, and not torch the wire thats connected.
Easy places to get power
ACC: Any fuse marked ACC
IGN: Any fuse marked IGN, sunroof, wipers, turn signals, windows
Constant: Anything marked BATT, the battery itself, and the secondary battery terminal (under hood fuseblock)
If you choose to tap a fuse, you don't want to put high current accessories on those taps. You will want to make use of relays (see below). For example, don't put 10 neon lights on your sunroof fuse and wonder why every time you open the sunroof when the neons are on, the fuse blows. Things like gauges, radar detectors, small things etc, are generally ok piggybacked on top of a stock circuit. Especially one that isn't always on, like the sunroof, windows, blinkers. When you have multiple things to power, or high current items, use your fuse tap to power a relay.