Tuesday, June 30, 2015

Wiring up the NC2 Miata for Android Auto

The Mazda Miata MX-5 isn't exactly new to the world, they released the 30 year anniversary edition just recently.  However, what I was wanting to change isn't exactly a simple plug and play.  Android Auto is something new from Google that I wanted to set up.  I also wanted to make sure all the existing features worked without problems like the steering wheel controls and the existing BOSE audio amplifier.  I've read up on multiple different locations but the documentation I found did not have everything I needed.  Instead, this was a piecemeal work to get everything working in a single shot.  Bear with me here as we are in for a bit of a technical ride.

Equipment


After reading a lot of different material about what headaches people have had, I made sure to get all the material I needed.

Head Unit: Pioneer AVIC-8100nex (Amazon was the cheapest I found)
Dash Kit: Metra 99-7519B (Amazon also available local in most areas)
Wire Harness: Metra 70-7903 (Amazon can be purchased locally, order two of these)
Line Level RCA: JL XD-CLRAIC2-SW (Amazon, but cheaper locally*)
Steering Controls: Metra Axxess ASWC-1 (Amazon best of the bunch by the reviews on several sites)

You may need some extra wire, soldering iron, solder, heat shrink (I used 3:1 with adhesive for a tighter bond), and electrical tape.  A side note on the JL RCA plugs, you can use any other brand you would like but be sure your grounds are solid to avoid alternator wine.

The main thing to make note of is the wire harness, you will need two of them.  Even if you are not going to be wiring up the steering wheel controls, there is a missing wire needed by the Pioneer AVIC units.  This is the speed pulse sensor wire which helps with the GPS positioning and speed warnings.  If the pins were not of a different size, you could have used one of the speaker leads but it just isn't possible.

Speed Harness


Pioneer Harness
Yellow: Constant 12V
Red: Switched 12V
Orange/White: Illumination
Black: Ground
Blue/White: Remote Switch (amp turn-on)
Light Green: Parking Break Switch (required)
Pink: Speed Pulse Sensor

The rest of them on this harness I was able to tie off and ignore.  The tips of the unused wire were bundled together and taped off to avoid possible electrical damage.

Metra Axxess ASWC-1 Harness (Steering Wheel Control)
Red: Switched 12V
Black: Ground
White/Green: Steering Switch

The remaining of these wires are completely unused.  However, keep them in case you ever decide to move to another vehicle.  For safety reasons, these remaining wires can be tied off and taped as well.

Metra 70-7903
This one is going to be the hard part of the wiring.  You will have to rob some of the pins from one harness to use on the other.  Using a very small jewellers screw driver you can remove the extra three wires you will need.  The colors used in the original harness are as follows:
Yellow: Constant 12V
Red: Switched 12V
Orange/White: Illumination
Black: Ground
Blue/White: Remote Switch (amp turn-on)
Gray: Right Front (+)
Gray/White: Right Front (--)
White: Left Front (+)
White/Black: Left Front (--)
Violet: Right Rear (+)
Violet/Black: Right Rear (--)
Green: Left Rear (+)
Green/Black: Left Rear (--)

As before, be sure to bundle the remaining unused wires and electrical tape as needed.  The speaker wires (Gray, White, Violet, and Green) are soldered to the Line Level RCA plugs.  This is done so the existing BOSE amplifier is not over powered by the high level line outputs.  Connecting this the wrong way will fry the OEM amplifier very quickly giving you a repair cost of roughly $900 for replacement parts.

Pinout chart of vehicle connector
This chart will help.  The missing pins you need are 1N, 1P, and 1I.  The wire for 1N goes to the Green/White wire of the ASWC-1 harness.  You will ground 1P by adding it to the existing ground at 1T.  The last of the missing pins (1I) will go to the pink wire of the Pioneer harness.

Here is a finished Metra 70-7903 harness

Getting it together


From here, getting the wire harness together is very simple.  Red to red, yellow to yellow and so on.  Pay close attention to the locations of the added pins and where they go.

The last bit is to bundle everything together as it will be a tight fit in the dash.  What I did was move the harness bundle off to the left side of the dash cavity.  The GPS antenna was positioned inside the dash as well.

In the middle of the test process


Last Note


One thing I did find out after putting everything back together, Android Auto will only work on the bottom USB port.  If you haven't set up Android Auto yet, you will need to make sure the parking break switch lead is properly grounded.

With everything installed, stay tuned for a real world review of Android Auto in action.  As always, feel free to ask any questions and I'll be happy to help.

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