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Getz connected to the head unit

25 Oct

Alright, now for the latest instalment. Firstly, I need to precursor this post by saying that I had very limited time to do this. Knowing that in advance is a good thing. The reason I mention it is that there are a few steps in here that wouldn’t need to be done, but I have because it means that I could pack everything up and return the car if I had to.

So, that said, I’m now at a point where I need to connect the amp to the front speakers and the head unit to the amp. Now, the way it works is that the head unit sends the music as a signal to the speakers. I want to introduce the amp into that loop, so I want the head unit to send the signal to the amp and the amp to them send the signal (amplified) to the speakers. (Not: Head Unit = the stereo unit, the place where you put the CDs etc)

The car currently has a wire that goes from the stereo to the speaker. I need to put a new wire from the stereo to the amp. Then I need to put a new wire from the amp to the speaker. However, if you think about it, I don’t really need to rewire the whole car. I can just tap into the wire going from the head unit to the speaker!

With that in mind, the idea of this post is to show how I’ve inserted two wires (per speaker) into the head unit area to by tap into the existing wiring. I will also make sure that it works (and be able to return the car on time with a working stereo) by temporarily connecting the two wires at the amp – that is the stereo to amp wire and the amp to speaker wire. Essentially I’m just lengthening the cables.

The first thing I had to do was pull out the headunit. To make this and future steps for this section easier, I also pulled out the chairs and centre console, which I can do in about 30 seconds now. See previous posts for instructions.

The headunit wasn’t too difficult to get out. To start with, the best way I found to do it was to get at it from the glove box. To do that…

  1. Remove all stuff from the glovebox. All of it. Otherwise, when you do the next couple of steps, anything left inside will be unceremoniously dumped on the floor.
  2. With the glovebox open, find the rubber stoppers on the left and right hand sides that keep the glovebox from falling open.
  3. A plastic square inside the glovebox corresponds with the rubber stoppers – get a fingernail under one of these and you’ll find it comes up pretty easy. (tip – don’t put pressure on the glovebox to do this)
  4. Gently pull the plastic square away from the wall of the glovebox and at the same time, push the rubber stopper from the other side. Rotate the plastic part a little as you go and you’ll find that it will come out pretty easily.
  5. Once both stoppers are removed the glovebox hangs nicely down out of the way, exposing a hole where you can stick you hand in to get to the stereo.

Now, for the next part you want to have really small hands – if you don’t prepare to get cuts and scrapes on your hands and arm. Stick you’re hand in the gap and locate the back of the head unit by feel. Gently push on it and see if it will come out. Also feel for the connectors that go into the back of the head unit.

There are two little metal clips on either side of the unit, not very big, but they are supposed to hold the head unit in. With something large and flat (eg butter knife or metal ruler or something) gently slip it down the side of the head unit from the outside, while pushing from the back of the unit. What you’re trying to do is disengage the clips on the side. It’s not too difficult, just be careful not to scratch anything on the outside. 

Once these clips come undone, you’ll find the unit will only push so far. You will need to disconnect one of the clips at the back of the unit for it to actually come out. When it does, just let it hang there.

Below is a close(r) up photo of the panel on the top of the head unit. This is a good one because it gives you the information about which wire goes where. We’ll need to know that when we connect the wires.

So, speaking of wires, it’s time to put the wires through. First task – cut the wire.

I said that there needs to be a wire from the stereo to the amp and then from the amp to the speaker for each speaker. This means 4 sets of wiring (8 if you count the positive and the negative separately). To measure how long each wire should be, get one length right first and then cut the others to the same size. We can o this by running the wire from the head unit (on the outside is fine) to the amp. Make sure it’s really slack so it accounts for bends and such.

Remember, longer is always better – you can cut it shorter, but you can’t cut it longer.

Two things first on best practice. Number 1 – the squarish wire should be positive and the roundish wire should be negative. If they are the same it doesn’t matter, but if that’s the case (and even if it isn’t), Number 2 – label all your wires.

A bit of electrical tape wrapped around the end of the wire is fine for labelling and avoids mistakes and uncertainty. The way I found easy to do this is to put the strips of tape on your jeans leg and then write on the with a sharpie (permanent marker).

The abbreviations I’ve used should be pretty straight forward…. plus or minus for positive (+) and negative (-), L or R for left and right (speakers) and then from the head unit to the amp (to amp) and from the amp to the speaker (to spkr). To make sure I put these on the right wires, I laid them out on the roof to see them all at once and then went through and labelled them.

This way it’s pretty easy to make sure that the positive on one end is the positive on the other end. You’ll need to do two sets of labels from what you saw of my leg above – one for each end of the wire.

Once you’ve done that (and I know it takes ages, but it will help down the track, trust me), we need to put all these wires in the same place, so we can tie them all together. I found that a bit of pvc tape wrapped around them at intervals is enough.

Beautiful. Now all we need to do is put it in place. I’ll let the pictures do the talking…

Next we need to connect the wires up. So, I keep going on about this, but the flow is headunit – amp – speakers. I’m going to take the amp bit out of it so I can test that everything works okay. I’ve also run out of time and need to put the car back together so this will hold in the short term, allowing the owner to use the system.

First we need tools!

You probably know the wire strippers and screwdriver, but the lego block looking thing is a wire connector. The idea is that the two wires are inserted into either side and then secured with a screw. Not the best way to connect them, but a good temporary way. I’ll be using these to connect all the wires at this stage so that I can make sure everything is working properly and then I can replace the connectors with twist, solder and heatshrink.

First, at the amp, use the wire strippers to… unh… strip the wires.

Then we want to find the Left Positive wires – there should be two – one to the amp and one to the amp and one to the speakers. We want to connect those two together.

Above you can see (well, in a blurry way) where I’ve connected both the positive to positive and negative to negative on the left speaker. Do the same for the right speaker as well.

Then once that’s done, let’s go to the head unit. At the headunit, find the coloured wire that corresponds with the wire we’re inserting. Ideally we’re splicing the wires into where the current wire is. Therefore, cut the wire, strip it and the connect one end (at the headunit) labelled “to amp” and the connect the other end of the coloured wire to the wire labelled “to spkr”. this basically brings the amp into the loop, uses existing wiring and should be great for us to test it’s all good. Use the diagram I had a picture up of earlier explaining what each colour is so you don’t get them mixed up. Check and double check as many times as you need to because it will be a pain to find out which one isn’t working if you have problems.

Clearly it goes green, red, orange, blue. I tried to keep both sides the same to make it a little easier. I know I haven’t used all of the connector space, but that’s fine. Remember these are temporary until we go through and solder/twist/heatshrink the actual wires. But if all goes well, we should have a fully functioning stereo the same as before, but with extra wire in there. 🙂

Last step is to tidy up all the wires so nothing gets accidentally pulled out. Then cable tie them and test. Did it work? Awesome. We can put the car back together and next time connect power to the amp!! If it didn’t work, go through and check each of the wires and ensure they are all connected properly and that the right wires went to the right places.

Catch you in the next post where we connect power to the amp !!! Almost done. 😀

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