Upon reading the following article.  The author (radcastro.com) and any associates will not be liable for any damages (direct or indirect) under the usage of this article.  By reading this artcle, you agree to waive any liability towards the author of this article.  Please perform this modification at your own risk.   

The following talks about the ripping apart your dash and installing/wiring a defi sports gauge.  Just to let you know.  This product is no longer in production.  However, in the event you install something more simpler...such as a tachometer.  This can help assist you on which wires to tap.  However, I recommend before you begin that you have a voltmeter, solderless connectors, long-length screwdrivers, a vise-grip and serious patience.  Oh yes.  Don't forget to disconnect the battery from the negative terminal.

Let's begin with some teaser pics.

Yes.  The gauge will give me a HUD type display.  Very cool and unique.

First pry out the vent that contains the clock and you'll expose the wires.

NOTE:  The following can be used also to take apart the dashboard.  This article doubles as a tutorial for novices that want to change the lights inside their instrument cluster.

Anyway...let's continue.  Go under the steering wheel and unscrew the top plastic case of the steering wheel.  You don't need to unscrew the viewable screws...just the deep ones.

This will then let you remove the cover from above.  Be careful not to break your plastic covers.

Then we go under the ignition and remove a little piece as shown below and remove the screws once they are exposed.  There should be two screws.

Remove the following screws as shown in the red circles below.

Carefully remove the panel in front of the instrument cluster.  Use two hands.  Don't follow this picture.

Remove the rest of the screws that surround the gauges

Remove the screw as shown in the red circle and carefully pry it loose with a screwdriver.  DO NOT TRY TO COMPLETELY PRY IT OUT.

Go to the other side of the dash and remove the little lever/button that open and closes the vent.

This then gives you a chance to pry out the left side without the vent's button flying at your face.  This gives you a chance to expose the harness that connects to the dash's light adjustment knob.  Disconnect the harness.

Once you do that, you will need to open the hood of the car and remove the unlatch the cable that changes the temperature of your heater/AC.  You will need to place a cotter pin on the cable so that it doesn't find itself in the firewall.  That would suck if it did.  Make sure that cotter pin is secure.  See below

Just to let you know...you will not be able to completely remove the dash but you will have just enough access to remove the instrument panel (the real important part) Well...at least I haven't figured it out...yet.  Anyway, just try to carefully move the plastic out of the way so that you can get access to the rest of the other screws that secure the instrument cluster.

Once you get all the screws, you should be able to move the gauges and wedge your arm/hand behind the instrument cluster. If you can, you should be able to feel the harnesses behind it.  Don't worry...you won't do too much damage as long as your hand isn't holding something sharp.  Just carefully disconnect the harnesses behind the instrument cluster.  Your hand should look like this if you've successfully removed one of the three harnesses.  Yes.  Three.

Once you get out all three harnesses...you should be able to shimmy the cluster to the side and end up like the picture below.  Note the red circles.  This is where you can change your lights to make them a different color.  It's simple as a twist of the knob.  I decided to keep mine green.  The bulb type is 194.  I will install raybrig lights in the future. 

Backside of gauges

and this....  Note the three harnesses.  You will definitely revert back to this image later in the article.  The pic below will be designated as Figure 1.  Hopefully, it looks like this when you take out the gauges.

Figure 1

Ok.  Please study the following diagram.  This was used under permission from Defi Shop.com

Now what do we do?  Well...we lengthen the wires by freeing them from their sleeves.

Then we grab one of the solderless connectors....

 and study the following illustration (Figure 2)...you can skip this whole article if you're a seasoned electrician or electronics veteran like my friend Chance (who helped me greatly with this modification and article)

Figure 2

If you remember the Defi digram with all those wires and colors...we will begin with the Defi's orange wire (IGN to 12V wire on instrument panel lights on).  This is the wire that feeds power to the DEFI unit only when the key is turned to the ACC/ON position.  We will get this power from the clock's grey wire since the clock turns on only when the key is turned to ACC.  Use the connector here...like so...

The next thing is the radio.  Since the Defi requires constant power (even when the vehicle is off)...we need to get this power from somewhere.  My friend recommended the radio's power wire.  After carefully looking at the electrical wiring diagrams...we ended up identifying the blue wire (with yellow stripe).  This may be different for you guys.  Anyway....yeah...we need to connect the Defi's yellow wire (+ B to 12 V Battery) here.  Read the message within the picture below...

So yeah...like I said in the beginning...having a voltmeter is a huge deal.  You can detect which of the wires are returning voltage (approximately 12v) while the car is off.  Of course, you will need to reconnect the battery to do this.

The next step is connect the ground wire.  No problem.  You can connect this wire to almost any metal part of the car.  I decided to you this bolt since it connects directly to the car's metal innards.

The next few steps are special.  With the yellow, orange, and black wires already tapped in...we have the red, blue, green and grey wires left.  Go back to Figure 2 to remember what the rest of the wires do. 

Below is a wiring diagram of the celica for my car.  This may or may not be the same for you all.  This diagram is inteded for the Celica 91.  I have a 93.  So it seemed to work.  You can never be too careful though.  Anyway, below is a diagram of the brown, white, and grey harnesses you saw in Figure 1.  You will need to tap the car's Tach wire with the Defi's blue wire using a solderless connector.  So connect the Defi's blue wire with the GRAY harness' 2nd pinhole...or the wire that connects to it.  SEE FIGURE BELOW! For me...it was a black wire. CAREFULLY STUDY THE DIAGRAM BELOW SO THAT YOU COUNT THE PINHOLES CORRECTLY.  LOOK AT HOW THE HARNESS IS ORIENTED TO CORRECTLY COUNT THE PINHOLES.  THE FASTENING TABS SHOULD BE FACING ABOVE

For the Defi's red wire...I connected it to WHITE harness' 7th pinhole (red /w blue stripe wire). 

Now, here's even the more special part.  You have to decide if you want to have the Speed Release Governor (SGR) Feature or not.  What is it?  It's basically a feature giving the Defi system the ability to limit the speed of your vehicle by becoming a bridge between the ECU and the speed limiter.  According to the Defi site, you can adjust the limits of the speed limiter through the Defi.  Interesting.  But seriously and in all honestly, I don't know if this is truly the case...but that's what I've read.

Assuming you want this feature do the following steps.  If not...do to the next step.  Personally, I didn't perform this step.  But here it is:

At this point we have two wires left - gray and green.  Both of these wires will affect a single wire - the WHITE harness 6th pin.  The wire for at least in this situation is blue with a white stripe.  Again, CAREFULLY STUDY THE DIAGRAM ABOVE SO THAT YOU CAN COUNT THE PINHOLES CORRECTLY.  LOOK AT HOW THE HARNESS IS ORIENTED TO CORRECTLY COUNT THE PINHOLES.  THE FASTENING TABS SHOULD BE FACING UPWARD.  The next thing we need to do is connect the Defi's green wire as close to the harness itself.  Then connect the Defi's gray wire.  DO NOT CONNECT THE GRAY WIRE BETWEEN THE HARNESS AND THE GREEN WIRE'S CONNECTION.  From front to back we should see the WHITE Harness, Defi green wire connected and then Defi gray wire connected.  You will then CUT the wire (blue with white stripe) between the two connections.  This will make the Defi the bridge between the two. 

Now, assuming you DON'T want this feature.  Connect only the Defi green wire and that's that.  Do not connect the Defi grey wire.  Just insulate it.  So yeah...I decided to skimp out on the SGR system to control the speed limiter.  Yeah sue me.  I don't want to have to keep setting a speed limiter in the Defi if the battery goes out or if I have to disconnect it.  The Defi will have several settings but it would be pretty annoying to keep setting it up.  Besides.  My car's engine sucks.

Anyway, I'll assume, you'll know how to put everything back.  Don't forget to connect ALL the harnesses, and other stuff.  Give yourself the chance to change any lights behind the gauges if you feel like it.  So is this it?  Well...other than mounting the display and the unit...you're pretty much good to go.  You can leave the unit on the rug or hold the display in your lap...this article was meant for wiring.  Thank you for your time.

For those curious to see the gauges without the window.  Here's your chance to install those reverse gauges.

Here's what the gauges look like after install.

Mounting area

Yeah....done.  Yay me.  Huge props to Chance Castro for helping me out with voltage and wiring basics.  You fuckin rock!

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