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Thread: Wiring a Head Unit

  1. #1
    Registered User wizeguy4's Avatar
    Join Date
    Mar 2002

    Wiring a Head Unit

    Can I get a sticky please?

    Wiring a Head Unit

    Hopefully this will give you a better understanding of Head Units and wiring them. For those who do not know a Head Unit is a radio and is usually the first aftermarket thing that a person does to their vehicle. You do not void your warranty when installing an aftermarket head unit even if you do it yourself as long as it is put in properly.

    You should always use a wiring harness when putting in a head unit. This allows you to use the wires off the head unit and then it will plug right into the vehicles existing plug that was being used for the original head unit. These are only about 15 bucks at most.

    When you are removing a DIN and a half or a double DIN (DIN refers to the height of the head unit. Aftermarket head units are usually DIN sized unless said otherwise) head unit and replacing it with a single DIN head unit, you are going to need an installation kit. What this does is cover up the empty area that you would have around the radio and also allow you to mount the radio into the stock location using the stock screw holes

    Every car is different as far as removing the original head unit is concerned. Some are easier and some are not. Some you just need to pull the trim piece off from around the radio and then unscrew the radio, while other will require removing heater controls and trim from around the gauge cluster, like a Kia does. Some have screws that are located in the ashtray area that need to be removed first

    For Ford and Volkswagons you are going to need to get a set of “keys” to get these radios out. You can get these at Best Buy for 5 bucks. All it really is, is a piece of metal that is double ended and has a little hook on each end that slide into the side of the head unit and allows you to pull it out.

    All GM vehicles will need an antennae adapter. It seems GM thought it would be funny to make their antennae smaller than the hole it needs to plug into on any aftermarket head unit. So you need to get an adapter that the antennae plugs into and make the plug bigger so that it will fit. So plan on spending another 6 bucks for this piece if you have a GM vehicle


    Ok, if you have not noticed yet, there are a lot of wires coming off of the back of the head unit also coming out of the wire harness. The speakers take up 8 of those wires (2 for each side. I have included a diagram of what a radio can look like. There are some wires that will be on your head unit that are not listed but I will get to those also. Also, in the picture it only shows one wire for each speaker channels, but there are really 2 they are

    White and White w/black stripe = left front speaker
    Grey and Grey w/ black stripe = right front speaker
    Purple and Purple w/ black stripe = right rear speaker
    Green and Green w/ black stripe = left rear speaker

    Ok that takes care of the speaker wires. If you are using an exterior amplifier for your speakers, then you will not need to connect them. There are also some other wires that are on the back of the head unit. They are

    Orange – Illumination (this means that when you dim your interior lights, the head unit
    Will also dim. This is usually not connected and has a tendency to blow fuses)
    Blue w/white stripe and also a blue wire – there 2 wires are used to send a signal out to an
    Amplifer to turn it on (remote turn on) and the other one is used for raisng a
    Raising a power antennae. Make sure you check which is which so you do not
    Connect them wrong!
    Black – This is the ground wire
    Yellow – this is constant 12V or the battery wire or the memory wire (which ever you like to call it)
    Red – This is the 12V switching wire or the ignition wire.

    Make sure you do not confuse the red and yellow wires also or else you will have problems


    Aftermarket head units will usually have at least one set of RCA’s on them. This can either be a set of wires coming out of the head unit or 2 plugs on the back of the head unit. If your head unit has a set of non fading sub output RCA’s, this means there is a third set of RCA’s on the back of the head unit. These are for the subwoofers and the volume of them will not change if you use the fade function on the radio. They remain constant.

    A lot of head units now are coming with a 4th set of RCA’s, which would be for a CD changer. And there is also a 5th set of RCA’s on higher end head units, which is for an auxillary output such as a DVD player or something along those lines.

    OK well I think we have now defined that big mess on the back of the head unit, so lets start connecting the wires.

    Now I know that since this is a guide, I should really only list the best way to make the connections, but that is not always practical. So here you can pick one. I will list them in order of how good the connections is.

    First would be to solder the wires together. This would make the best connection. After the solder cools in about a minute, wrap in electrical tape.

    Then there is wire nuts or crimps– they have different names to different people but basically you put the 2 wires into this plastic thing and crimp it down around the 2 wires, connecting them this way.

    Then there is good ole wrap and tape. Stripping the wire and twisting them together and then wrapping up with electrical tape. This makes the worst connection, however I would venture to bet that 95% of all head units in people’s cars are done this way!

    Well the connections are made, plug in the antennae and turn on the power and see if there is any noise coming out!


    If the amplifiers will turn on and play music when you have the radio on but now when you put in a CD – you have the remote turn on wire and the power antennae wire switched.

    If you lose the time or the programmed radio stations every time you shut off your car, then you have the red and yellow wires reversed.

    These are the 2 most common mistakes that are made.

    Hope this guide helped you out. If you are still having problems, or have a specific question about your car or the head unit itself. go to and pot your question in the Head Units section.


  2. #2
    Blazin no mo Forklift's Avatar
    Join Date
    Dec 2002
    Vancouver WA
    btw being an installer, I know that most of the new cars out right now require an ant. apaptor. Most Nissans from around 87+ need one, Most GMs from 87 and up need one. VWs, BMWs, and just about everything else from 02+ need one except a Ford.
    If you own a new body style Sable or Taurus , have fun. The radio controls might be in the dash but the radio is in the truck next to the ant.!
    Also if you ever hook up a radio and get no sound, check for an amp turn-on wire and hook up the turn on wire coming from the radio. Thsi usually means you have a factory amp and not that the radio doesnt work so chill and dont come crying to me cuz you tried to hook it up yourself!
    04 EC Silverado 4.8L,Pioneer, Rockford Fosgate, K&N, Viper, ACT, USSpeedo, Matrix, Whelen, Blackbear, 22" Eagles, Nittos,Russel,Magnaflow
    85 S-15 2.5L/4spd, RF P1 subs, highs & T4004, JL 250/1, SD 4-link, AIM LCAs, 1/2 valves, Blazer interior, 17" Eagles w/BFGs, phantom grill, 140 amp alt

  3. #3
    Registered User
    Join Date
    Jan 2006
    Best Buy Prices:

    Dash Kit: $18.49
    Wiring Harness: $18.49
    Sable/Taurus Harness: $117.49
    GM RDS Harness: $119.49
    GM Ant. Adapter: $12.49

    If your vehicle has RDS, and you dont want to pay the $119.49, get a regular harness, but be ready to spend about $800 at the dealership when it burns up your instrument cluster.

    Also, some vehicles are ISO mounts which means you dont need a dash kit. Slide out your radio, and if the can fits in the slot without movement, just press down the tabs, and slide in the radio. If you buy a dash kit, and dont need it afterall, you better hope its unopened

    If your factory radio has the ground wire attached to the back of the radio, you just need to connect it to the black wire on the aftermarket radio harness. Dont forget to ground it.

    If you cant connect the wiring harness to the one provided with the radio, then you dont need to be doing this. Its very easy to do, and most vehicles take about 30 minutes.

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