When it comes to wiring up HU's to car power and speaker wiring, it should be done properly.
Signs of a bodgy installation:
- Twisted and taped wires (power or speaker)
- Messy and disorganised wiring
- Stereo power cutting out (not CD skipping) when driving over rough road
- Distorted sound from speakers
- Distortion at high volume levels (not speaker overdriving or pushing the amp too far)
- HU Battery + wire tapped into a small wire, like a clock memory wire.
- Engine noise being inducted into system (although this even happens in the best installations)
- Fuses blowing in car's fuse box when stereo running at high volume
- Wrong wiring used to power head unit (too small gauge of wire)
NOTE: Minimum gauge for wire used to power a HU should be #17, which can handle 15A at 12V, this is usually a good size for most head units.
Signs of a good installation:
- Labelled wires
- Molex plugs/sockets, crimp connectors or terminal strips used
- HU Battery + wire connected thru a 15A fuse to battery positive using proper gauge cable
- Wiring that is kept together with cable ties or loom tube to organise everything
- New speaker cable has been run to all new speakers in the car
- Little or no engine noise inducted into system
- No wiring is loose or causes stereo to cut out when disturbed
- No distortion
- Right gauge wiring used for all parts of the system
- Wiring that has been spliced is either soldered and taped or soldered and insulated with heatshrink
Soldering/Taping/Heatshrink, Crimp connectors, Molex's and plug and play connects are the only ways.
For cars with a OEM plug that has every wire that you need, tap into by stripping the wires and soldering and tap in the factory wires in. You will have to determine which wires are what.
If you dont plan on ever reinstalling the factory head unit, cut the OEM plug off, determine which wires are what and use whatever connection method you prefer.
To make it plug 'n' play (good if you aren't technically inclined or dont feel confident tapping into the cars wiring), buy an Aerpro wiring harness, which is either a plug that fits the cars wiring harness with the standard colour coding wires coming out of it (yellow for B+, red for acc+, black for ground, and the standard speaker wire colours), then u just wire these to the stereo wiring harness using whatever connection method you prefer, or get a direct plug 'n' play harness which has the plug for the cars wiring harness and the plug to fit the head unit u are using, this is completely plug 'n' play and doesnt require any splicing or reconnections.
If the car doesnt have a OEM plug (been cut out by a previous owner) just determine which wire does what and then connect them using your preferred method.
If the car is an older one (pre 1990) and the radio didnt have electronic presets or a clock that needed 12v unswitched to maintain (like mine), and therefore had no unswitched 12v in the factory radio harness, get a wiring diagram of the car and find the colour of the feed to the ignition switch from the battery, and tap into that using a wire that is the same size or bigger than the constant 12v wire of the head unit. A good all-rounder for all head units is Jaycar #17 red + red/black, use red for power and use red/black for ground. Make sure that you fuse the new constant wire for the stereo with either a 10 or 15A fuse.
And in regards to speaker wiring, I recommend using all new wiring throughout the car no matter what car it is. I use Jaycar #18 gauge heavy duty clear sheath with black trace on one wire. I use #13 Jumbo speaker cable for my bridged amp/sub setup.
Heres some pics of my wiring.
My constant 12v tap from the ignition switch wiring harness
My new stereo wiring all wired to molex connectors except for amp turn-on (blue wire)
Edited by ben1990, 12 June 2007 - 12:43 PM.