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| By: UKinstaller on Fri, 3 Oct 18:43:19 -0500
| | One of the most common mistakes made in car audio is that people instantly think that they have to cut off their wiring harness for the factory radio because it doesn't match up with the aftermarket one. This could not be more false!! For almost every vehicle, the installer can purchase a wiring harness for less than $20 that will prevent a potential MAJOR headache when it comes time to do the install. However, in the following situations, it may be necessary to "hardwire" the new head unit harness into the factory wiring without a wiring harness.
1) you or someone else cut off the factory harness.
2) someone stole your gear and cut it off in the process. this is fairly common during stereo theft.
3) you have an older car (1984 or older), or have a car that there is simply no harness made for. Examples include various volvos, almost ALL mercedes, and any exotic or rare car.
However, all is not lost if one of those situations apply to you. Here's the proper way to hardwire your new head unit into your car.
First and foremost, you will be identifying and connecting anywhere between 11 and 14 wires, depending on the vehicle. More often than not, it will be 11 wires, which includes a constant power wire that stays hot when the car is off, a switched ignition wire that only has power when the car is on, a ground wire connected to bare metal, and 8 speaker wires. There are two speaker wires for each speaker, so adjust accordingly for how many speakers you have in your vehicle.
Before you get started, you will need the proper tools. You'll need some wire strippers, a digital multimeter, electrical tape, solder, and a soldering gun. If you prefer to connect using crimp caps, do so if you please, but i always prefer tape and solder for the best connection possible. You'll also need the battery off of a 9V or smaller drill to test your speaker wires. A regular 9V duracell battery or equivalent will work fine, too.
To begin, I always find my speaker wires first. This is the most tedious part, so i like to get it out of the way. Disconnect the battery of the vehicle so you don't blow fuses for the head unit. Next, strip back all of the wires that are available to you. I like to grab the all together and cut them all an equal length to make it neat.
Once you have all your wires stripped back, it's time to begin testing them. Grab any single wire. Hold it against a terminal on the battery and one by one go through and tap every other wire against the other terminal of the battery until you hear a "pop". When you hear a speaker popping, you have correctly identified the wires that run directly to it. If on the first attempt at popping a speaker you don't find one, pick up another wire and repeat the process. They will eventually come, and the more you identify, the fewer wires you have to mess with, and it will come quicker and quicker. If you have tried to pop every single combination of wires to no avail, your vehicle has a factory amplifier that needs to get power in order to send power to the speakers. If this is the case, stop here, because identifying a turn on lead for a factory amp is almost impossible without a wiring diagram. I can identify them without a diagram, but i do this every day and, trust me, it is HARD to do. The steps involved are too tedious to explain via text. If this is the case, send me a clubmail and i will give you the wire color to turn on the amp for your specific vehicle.
Repeat the process until you have properly identified the four speakers in the car. Once this has happened, it's time to connect them to the head unit harness. On the head unit harness, the speaker wires are as follow:
front left speaker positive - white
front left speaker negative - white/black
front right speaker positive - grey
front right speaker negative - grey/black
back left speaker positive - green
back left speaker negative - green/black
back right speaker positive - purple
back right speaker negative - purple/black
figuring out polarity for the factory wiring colors is almost impossible to do, so generally i don't worry about it. I can tell no difference whatsoever in front and rear speakers if the polarity is backwards, and you probably won't either. however, if it sounds like some speakers sound better than others, swap the polarity on the speaker accordingly. Many people will argue that they can hear a differerence in sound, but i sure can't. It's very noticeable on subwoofers, but not on front and rear speakers.
Connect your 8 speaker wires accordingly to the head unit harness using whatever method you prefer. As previously mentioned, i prefer tape and solder, but if you use crimps, just make sure they are secure. If you use tape, make sure they are NO strands of wire sticking through. This can cause problems.
After you have connected your eight speaker wires, go ahead and seperate the remaining wires so that NONE are touching each other. Go ahead and reconnect the battery, but leave the vehicle turned off.
Next to identify is the ground wire. Turn your digital multimeter to "continuity" mode. Put one lead from the multimeter to a known ground on the vehicle (any bare metal, or the cigaretter lighter). Go through and touch the other lead to each remaining wire until your meter signals continuity. Once this happens, turn on your headlights and make sure it stays continous, because illumination/dimmer wires can read ground, tricking you into thinking they are ground wires when they really aren't. If everything checks out okay, go ahead and put one lead on the multimeter to your new ground wire that you have located, and go through and test each remaining wire with the vehicle turned off. When you come across a wire that reads 12 volts with the car off, that is the hot wire. Connect it to the yellow wire on your head unit harness, and immediately wrap it in tape or crimp it. If it touches anything, it will blow the fuse, so it's best to insulate it as soon as it's connected.
If you can't locate the hot wire, you either have a bad ground or a blown fuse. Check all your fuses, and if none are blown, play it safe and go ahead and make a new ground wire. Connect a ring terminal to a wire, shoot a self tapping screw through it into BARE metal on the car, and there's your new ground. It's that easy. Many people recommend making a new ground on any HU installation, but i use factory when available because it's easier and works exactly the same.
Many nissan's, mitsubishi's, and chrysler/dodge's will not have a ground wire in their harness, so you will have to make a new one regardless.
Once you have located the hot wire, all you have left to do is locate the switched wire and you are done. Turn on the car. Run one lead from the multimeter to ground, and test each remaining wire until you have 12 volts. Turn the car off. If the voltage drops to zero, that's your switched wire. Connect it to the red wire on the head unit harness, and you should be finished.
The only things that I really can't tell you how to do via text is locating the amp turn-on wire and the power antenna wire in a vehicle. Shoot me a clubmail, and i'd be more than happy to give you the colors.
Well, that's all there is to it. You have successfully hardwired your head unit into the factory wiring without a wiring harness. Pat yourself on the back, because it's difficult and can be incredibly frustrating. If you don't feel like messing around and doing this yourself, take it to a local shop and they can do it for you for around $25, plus cost of installation if they install it, too. We charge $22 at circuit city.
If you want wiring diagrams for your specific vehicle, shoot me a clubmail and i'll send you all your power and speaker wire colors, along with any tips that i know about the car. I have diagrams for almost every vehicle ever made after 1984. GM and chrysler go back to the 70's.
Please don't hesitate to send me a clubmail if you have any questions/problems. I'd be more than happy to help out.
-UK
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