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Tutorial - Making connections between head unit and car wiring properly. UPDATED AND IMPROVED


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#1 ben1990

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Posted 14 February 2007 - 10:52 PM

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
Posted Image

My new stereo wiring all wired to molex connectors except for amp turn-on (blue wire)
Posted Image

enjoy :)

ben

Edited by ben1990, 12 June 2007 - 12:43 PM.


#2 Corksil

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Posted 15 February 2007 - 09:55 AM

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.

#3 Shinanigans

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Posted 15 February 2007 - 05:30 PM

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 :lol:

Edited by Shinanigans, 15 February 2007 - 05:33 PM.

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#4 Alex (rbimdxe)

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Posted 15 February 2007 - 06:24 PM

Shinanigans, on Feb 15 2007, 05:30 PM, said:

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 :lol:

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.
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#5 Shinanigans

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Posted 15 February 2007 - 08:32 PM

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

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Posted 17 February 2007 - 09:26 PM

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

#7 IvanTheTerrible

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Posted 21 February 2007 - 07:34 PM

Posted Image
narva

#8 grant collins

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Posted 22 February 2007 - 05:39 PM

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.

#9 Shinanigans

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Posted 23 February 2007 - 03:40 PM

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? :nea:

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

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Posted 23 February 2007 - 03:50 PM

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
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Cide, on 12 February 2010 - 03:37 PM, said:

OMG :shok: i didn't even notice the adams apple the first time...

#11 Poisoner

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Posted 23 February 2007 - 03:50 PM

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.
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#12 SAS

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Posted 23 February 2007 - 05:19 PM

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!


#13 Pritchy

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Posted 23 February 2007 - 10:41 PM

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

Posted Image

#14 ener

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Posted 24 February 2007 - 01:43 PM

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
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#15 Pritchy

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Posted 24 February 2007 - 02:35 PM

the advantage is that it happens all in one step





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