Ok, I have seen too many bodgy stereo installations, and admittedly I have done a bodgy install (only cos it was my cousins van, a cheap HU and the fact he wanted it done quick!)

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.
OR
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.
OR
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)


enjoy

ben

Where might one go about getting molex or similar connectors? I didn't see it in your post. I like this method and methinks that I shall adopt it.

I had "Mycar" (man i miss those shops... awesome time killer browsing) do an install in an old car of mine and they used a molex setup on my amp so i could remove the amp and subbox if i needed to. Made things nice and snappy when i needed to get the sub box out to move some gear. Wouldn't have a clue if it was detrimental to the system or not! Too long ago!

On my current car i used individual connections, just because it's what i find easiest to work with now.
http://www.caraudioaustralia.com/forums/in...st&id=11665

I'm interested in how you go about connecting the wires to the actual pins inside the molex. I've played around with molex plugs for case fans inside my PC and there's no way i could have managed to get soldier down inside them! haha

crimp connections.

when you buy the molex plug, the pins come seperate to to the plug. you attach the wires to the pin or socket(crimp+solder), and then insert them into the plug, where they lock into place via a hole in the plug and a tab on teh pin/socket.

Ahhh, ok. Hmm, might have a look at them next time im in the hardware store. Cheers!

pretty much all electrical stores will have the connectors , I know my local Jaycar has a good range of them

narva

sorry but why would u cut the oem plug out of the car? why not just strip the wire's and inch or so back from the oem plug and solder the after market onto the oem wiren? u cant tell me that cutting off the oem connect and adding one of these connects has any up side.i can understand if u were fitting a set of rear's to something like an early 90's model pulsar and u were getting the rear speaker wires from under the front seat's (depending on model) and u wanted it to look factory at the seat conesting but appart from that i dont see a need.

Why do you need to keep the OEM plug in that case? Are you talking about stripping back the shielding on the original loom and making a T intersection for the new wiring?

Personally, cut, solder/crimps and tape is the only way imo. Cut what you have to and run new what you can.

OR if your stock wiring plug is still there. You can get an adaptor from aerpro that makes a HU install plug and play.

http://www.aerpro.com.au/list.php

its good to maek good connections im glad someone tookl the time to do it. tho u dont HAVE to use 17g wire friect from the battery using a 15A fuse alot of HU still only have like a 10A fuse in them. if you dont plan to use the internal amp i.e. rca outs only altho most hus u cant turn off internal powersupplies but it will still draw only liek 2-3A most of the time(unless u are using motorization or say a 7" screen or the likes)

its good to be speciic but its also good to be general. "an appropirate size power wire as thick or thicker than the new aftermarket HU with an appropriate fuse. my hu has a 20A fuse in it but i will not be using the internal amp which i can switch off(alpine9815) so ill be just putting a 7.5 or 10A fuse in. as this is what my cable is rated too and the HU should not draw more than that.

yeah ive blown 3 amp main fuses before on pioneer h/u-just basic unit running all from rca but only when fair cranking it.

just one thing though-distortion at high volume does not necesarily mean dodgy install, possibly but not definately. most h/u could distort most factory speakers, and even good speakers when the internal amp is pushed to far.

and sometimes you mite not need to run completely new speaker wires-(from hu)-would be a very thorough install indeed but i don't think always necesary.

sometimes you get lucky with factory plugs. ive found plugs-mainly speakers that will connect to the narva plugs-BONUS!

Just found these don't know if any one has tried them, they look like they would make installs quicker and easier, they are made by Narva

whats the advantage over that to say normal heatshrink, is it that that is 20times more expensive?
i guess you could always twist and tape/heatshrink or both it just means its slightly weaker

the advantage is that it happens all in one step

^ that is awesome. Cheers for that info!

yes im talikng about stripping the factory wire about an inch behind the oem plug and maken my connection there.because im not talkin about behind the h/unit under the d/seat or p/seat depending wat yr model.They have a male or female (i can remember which one it is) plug that u can plug into and run ur wire's up to the h/unit instead of running wires down from the back.im sorry but i really dont see how cutting the oem plug from behind the h/unit is pro im not sayin it's not im just saying that keeping or leaving the plug doesnt make it pro i actually fit for a living and i prefer to leave the oem plug there just faster for remove refit's.

If you are running your 12V directly from your battery what size cable should be used? is something like 10G ok? Also, do you just connect that up to the wire coming off the harness?

Should a seperate ground be run as well?

cheers

10g is probably too big - maybe use something like 14 guage


In my car I have all stereo power coming through the same distro in the boot.
I've run a 8g power wire from the back up to the front of the car, and it powers the headunit, screens, and then when the xbox/dvd player was there it powered them also.

I was going to use #10 because thats what i had lying around, but i though it was overkill so just threw some jaycar #17 red and red/black in, that is a good all-rounder.

And I didnt cut the OEM plug out of the car because it wasnt there. there was a 4 pole harness with a black/white 12v acc wire, which i have split to: one molex pin for the stereo for the ACC+ wire, to the cigarette lighter socket positive (new socket, old one rusted), and to a switch to control an green underdash neon.

There's the illumination wire to the lighter socket as well, and if my head unit has a dimmer wire I'll just tap into that.

I tapped into my battery feed to the ignition switch with one of those scotch-lok connectors, then ran it thru a 15A blade fuse, thru the red side of the #17 wire and the other end goes into one molex pin for the B+ stereo wire. Then i grounded the red/black side and attached the other end to the last remaining molex pin on that plug (3 pin)

And even if the OEM harness had of been there, I still wouldnt have got a 12v unswitched wire, as the factory radio didnt have electronic presets or a clock. I would have got a bunch of crappy factory speaker wires, an illumination wire, a ground and a acc+ wire. thats it.

And the factory speaker wiring had been cut out by the previous owner, plus I put door speakers in and had to run wiring for that, so I ran new speaker wiring throughout the car.

And the factory ground was crap so I just cut that out and made the new grounds as above.

I would have soldered and taped the wires instead of using molex connects, but this makes it easier should I want to change the head unit. I crimped and soldered the wires onto the molex terminals.

Ive done installs for other people and yeah I've just tapped into the stock wiring by stripping the wires an inch back from the plug and soldering the wires on and taping it up.

Or if i can I went and bought a plug 'n' play harness, like when i did a 2000 Lancer, i didnt wanna hack the wiring up.

If it hasnt got an OEM plug thats of any use keeping, I just cut it, and solder/tape.

I never just twist and tape. Never. Only once where a mate wanted a stereo put into his van QUICK, so i just stripped plenty of insulation off and twisted and taped it, was just hooked to front factory speakers. ran a constant from the battery, thru a 10A fuse under the carpet up to the dash. Still working today so yeah.

Other good connectors to use would be male bullets on the stereo wiring and female bullets on the car wiring (to prevent anything shorting out on dash metal)

I will get better pics up soon in the first post.

It's interesting to see what people call good and bad installation techniques, some valuable tips here, but I notice one thing about Ben1990's wiring. Not a critisism at all but I wonder why you've used a 'scotchlock' to connect your main power feed in the top photo. I learned very quickly when these little beauties first came out that the best place for a bag of them was in the bin, they are notoriously unreliable and I havnt used them for years. The best thing you can do for wiring in that situation is to solder them.
I'm a fan of soldering stuff together and I get almost no comebacks that are wiring or connector related. The use of molex connectors is nice if done properly, but I'd only use them if it needs to be disconnected regularly. If your install is going to stay in for a while, soldering the wires is by far the best way.
Leaving the original factory plug in place is also a good idea, I've cut quite a few off cos they come in handy when you need to wire a factory deck but I've been caught out too many times when going back to restore a customers car to original and finding that I havnt got a factory plug to use. Embarrasing when it was me who cut it off, so I just leave them intact now.

Mike

agree totally with Mike S

esp. scotchlocks, they usually come in some install kits, and then come out and into the bin.

i like deutsch plugs a lot too but theyre kinda expensive... and in some cases overkill. but vehy nice.

+1 scotch locks suck.

but other than that that is wiring work to look up to.

Just to add, bundle up and tape/heatshrink together any wires you're not using, same goes for cables that are too long etc.

I used spade crimps on the last one I put in my car, then taped up a big bundle of the wires and cable tied it to a nearby spot out of the way. Nice and neat.