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Discussion Starter · #1 · (Edited)
Hey folks, about 4 months ago I started the process of installing a new Nexus 7 in my dash, and I had a couple blog posts that I wrote and had linked to here in the General Discussion section. I've decided to come back and format everything for E46Fanatics to hopefully help some other people out. Anyways, onto the DIY. This one's a long one, folks.

My Car:

E46 2004 325i Facelift 4 door. Stock sound system (component speakers, etc).

Parts:
  • Nexus 7 2013 ($199 @ Bestbuy) - I purchased the 32GB version for $239, as I wanted the extra storage. Probably not necessary in the long run, but I like the peace of mind.
  • E46 Carputer Tablet Bezel (custom-made from Richard @ MyBimmer.net) - This is a custom made tablet bezel, and it's brilliant. It does cost quite a lot but the fitment is absolutely brilliant, and it looks OEM. The only difficult part was getting the tablet to mount to the bezel, which I will detail later on in the DIY.
  • JVC KD-X250BT or equivalent ($120 @ Bestbuy) - Really doesn't matter what head unit you get, the main thing I needed to make sure was that there was no CD player functionality. The added depth (front to back) prevented me from fitting the unit behind the tablet in the console, so I needed something small that would fit, but still have decent features. I wanted bluetooth, auxiliary input, USB input, and radio if I ever want it, and this does all of that.
  • HVAC Relocation Kit ($54 to $87 @ ECSTuning) - The one you pick here depends on your car, look through these options and find the one that fits yours. I have yet to use one of these in my car, the HVAC fits well enough without the relocation kit, and only pops out a few inches when I accelerate quickly. It's not enough to be a nuisance, so I'll do it when I have fixed all the other issues with my car.
  • Metra Axxess ASWC Steering Wheel Control Interface ($50 @ Amazon) - This lets you use your steering wheel controls on the new head unit we'll be installing. This is really important to have, because once you install the tablet, the head unit can't be accessed unless you pull the tablet out of the dash. Ergo, the only way to control volume or stereo mode is with the buttons on your steering wheel. Play/pause and next/prev will work on the steering wheel too, but the tablet will have that functionality as well.
  • 12V to 5V DC/DC Regulator ($5 to $8 @ Amazon) - This guy will help us power the tablet using the 12V power from below the cupholder/eurotray. I'll get into that later.
  • Metra 70-8590 (2x) ($6 @ Amazon) - Yes, you need two of these. The single harness comes with all the necessary pins for the head unit, but lacks a pin 7 lead - which is required by the ASWC module. To solve this I bought another harness, and used one of the leads from that harness and put it into the other. Problem solved. I'll go into specifics later.
  • Soldering iron, heatshrink wrap (multiple sizes), solder, wire snips and strippers, 18 to 22 gauge wire (solid core or stranded works fine), zip ties, a microUSB cable (for the microUSB end, we'll be cutting this one in half, so get something cheap). Silicone adhesive for securing the tablet to the bezel. A multimeter is unbelievably helpful when doing wiring, especially checking for 12V signal on the connector we'll be using, where it's basically almost necessary.

The total, not including the small things in the last bullet point comes to roughly $625 USD. I work for Best Buy (and therefore have intentionally avoided linking to any of their pages...) so I paid considerably less with my employee discount. Looking back on the total cost, even at $625 the end result is totally worth it.

DIY:

I'm going to be brief with the components of the DIY that can be found elsewhere. Basic disassembly instructions will be written, but I'm not going to provide pictures for any of the disassembly because there are a hundred million guides on taking out the entire center console of these cars. Use this guide for removing the armrest and cupholder area, and for the rest, read this. For the second guide, no need to remove the shifter knob unless you know it'll come off easily. Makes things easier but it's not necessary.

Remove everything from the center console (armrest trim, rear seat cigarette tray, eurotray/cupholders, shift trim and boot). The current "scaffolding" that keeps the stock head unit and HVAC controls in place also needs to come out, because it's going to get in the way of all the stuff we're going to cram into that spot. So take out the framework and stash it somewhere in the event you ever want to put the stock stereo back in. There are a couple screws that keep it in place, so just undo those and the entire bracket should come out.

Let's move down to the armrest area. Yours should look similar to this, without the wiring already finished:



Just above the parking break boot, you should see a hole in the foam lining of the interior. Tucked into this, should be a small 18 pin header, which is actually designed to be used with an in-car cell phone. Seeing as it's probably OK to assume nobody will ever need to use the in-car cell phone feature, we're going to utilize the switched power source on this header. It will be powered when the car is on or in accessory mode, just as a normal head unit should be. This will be the source of power for our tablet. It's also why we need the 12V to 5V regulator, which you can see in the picture is already hooked up. Here's a picture of the 18 pin header, a bit taped up, but the header nonetheless:



If you for some reason can't find the header (it's pretty easy to find, just make sure it's not tucked under the foam), you may be unlucky enough to have a car which was not pre-wired for cellphone capability. An easy way to check is to open your trunk. Check the back left of the trunk lining, near the hide-your-illegal-substances box. You'll see a small black and white badge, probably more than one. It'll tell you if your car is pre-wired for a phone. It'll look similar to this:



If you don't have the badge, then you're SOL for the cell phone connector. The alternative would be to tear apart your existing glove box flashlight connector with a 12V socket like this guy has done. BMW has a part number floating around for an OEM adapter, but has since discontinued the item. There are a few you can find on eBay, but most are ridiculously overpriced or not OEM. Build one yourself!

Onwards. Your header probably has latch connector on it, so you'll need to remove that, which is pretty easy, just push in the tabs on the side and pull off. Once it's off you'll see the main connector as it is in my picture.

I had a lot of trouble figuring out which pins did what on this connector, and there seem to be a lot of different pinouts floating around the net. I finally settled on the X4545 connector which has a pinout that can be found on this page. You're looking for +12VDC and ground. There are two brown wires, ONLY ONE OF WHICH is actually ground. On the connector you can see four numbers, two on each side. One side has 1 and 9, the other says 10 and 18. These are the pin numbers. How you connect to these wires is up to you, you can use solid core 22-24 gauge wire and stick them in the top of the connector, or you can cut the wire (or pull the wire out of the header) and solder everything in. I took the lazy way and stuck solid core in the top, but I'll be going back later to solder and heatshrink everything (as you should do the first time around).

The pins you're concerned with are 2 and 6. 2 is the brown ground (1 of 2 brown wires) and 6 is a purple wire with a white strip. This is the +12VDC. Again, do not use the pin 7 brown as ground. It's not actually a ground. Double check with a multimeter and make sure you're getting 12V across those two leads when the car is on and when the car is in accessory mode (position 2).

Those two leads should be soldered into the 12V to 5V regulator. Make sure you use the correct side of the regulator. One will say IN the other will say OUT. Ground to black, +12VDC to red. Heatshrink your connections.

Run the two leads from the output of the regulator (again, solder/heatshrink properly) up, through the shifter assembly as shown here:



There should be plenty of space, just make sure you've taken out the center dash first, otherwise you can't run your wires up the back into the head unit area.

On the end of these wires, you want to add your microUSB connector. Any old connector will work, preferably use the smallest connector end you can find, as large abnormal ones may not fit properly in the space that you have. You'll see how confined the port is once we get it attached to the bezel. A standard USB cable contains 4 pins. They are colored (almost always anyways) red, black, white, and green. Red is +5VDC, black is ground, white is data (-), and green is data (+). Some USB cables will only contain red and black wires, because they are only intended for powering something. This is often the case when you take a microUSB plug from a wall charger, or something never designed for data transfer. I'm not sure if this will have a negative effect on charge rate, but I would use a data cable to be safe. The reason being, you need to short the data pins together in order for the tablet to charge at full speed. Strip the green and white wires, twist them together, and lightly solder the twisted strand. Heatshrink it and tuck it back. Your +5VDC from the regulator that we wired a bit ago should connect to the red wire on the microUSB connector, and the yellow wire on the regulator to the black wire on the USB connector. Remember that most regulators have a yellow output ground wire, not black. Solder and heatshrink appropriately.

Now's a good time to test the charger on your phone or the tablet. Devices will charge at different rates, so test them with the Battery Monitor Widget. (It's funny, because Battery Monitor Widget... BMW... heh.) This will tell you the charge rate in milliamps. In order to keep the tablet in the car and avoid having to charge it elsewhere, we need to make sure that the tablet loses minimal battery while the car is off, and it also needs to charge as much as it can when the car is on. To be safe, make sure the widget reports at least 750mA charge rate. Anything less, and you may run the risk of charging slower than the tablet will run out of battery. In my case, the tablet loses almost no battery when it's idle. I'll go into depth about battery savings and tablet software later in the DIY. To put things in perspective, my phone (Galaxy S4, Verizon) charges from the factory cable and wall wart at about 1900mA. The Nexus 7 only likes to do about 1200-1300mA off it's own factory charger. Different hardware will behave differently, so if you're using something other than a Nexus 7, this is something to keep in mind. This was one of the main hurdles of the process, and I'll be providing as much information as I can on that process a bit later.

If you haven't already, pull out your stock head unit and detach the harness from the back. It may take some force, but if you can't do it by hand, get a flathead screwdriver and use leverage to pull the header clip UP. It will pull very far up, and will definitely take some force before it clicks out of place. The header cable will pull outwards away from the head unit once you have pulled the lock mechanism up properly.

Next we're going to put in our new head unit. Because we need the tablet to be the front-facing item, we're going to have to figure out how to get the new head unit to rest sideways and back. This is the only way to get it to fit, as it's much longer than it is wide.

Here's how I fit mine in. Granted this picture is taken after all my harness wiring was done, this is just to show how my USB cable was connected and how the head unit looks in the dash.



It looks pretty decent for not being secured in any manner. I've never had any issues with rattling, there's a lot of wiring stuffed in there which I think helps with that tremendously. There's just enough room after the head unit to put the harnesses and the ASWC module.

Make sure that you follow your proper instructions for your head unit, and solder/heat shrink all of your connections to one of the harnesses you purchased. Once you've done that, open up the second harness and pull out one of any of the pins. I used a red one, and then marked it with a little piece of tape that's labeled "ASWC". The best way to remove these pins is with a jeweler's screwdriver, but not everyone has one, including myself, so I just used the smallest screwdriver I could find and managed to wiggle the wire out of the harness. Pop it into the other one in pin #7, using this diagram:

NOTE: IGNORE THE HIGHLIGHTED PIN 16. This is the only decent pinout I could find, and it happens to have that one highlighted. To repeat, you are concerned with pin 7. You may also be able to find a diagram in the head unit's manual.



Make sure the metal wings on the connector are flared out so it doesn't pop out later. If you're feeling iffy, give it some hot glue. Mine didn't fit as far in as the ones that came in the harness originally, but it works fine nonetheless. Here's the harness after I put the new pin in:



The red one on the right is in pin #7 and is what we needed for the ASWC module. Now, we need to solder in the ASWC module. Follow the instructions included. If I remember correctly, the ASWC module instructions said to solder the pink wire on the module to the pin #7 lead we just made. Do so and follow all other instructions. In my case, I believe I had to solder the pink one as mentioned, as well as splice the red and black wires into my existing red and black power/ground on the harness. All other wires on the module were folded back and zip-tied. Here's the end result:





And now our wiring is done. At this point you should test everything, because everything from here on out is cosmetic stuff or related to the software on the tablet. Make sure the tablet charges, make sure the power is switched and is off when it should be, and on when it should be. It may also be a good time to program everything you need to for your head unit, as it'll be difficult to get at the menus and dials once it's in place. Set up everything you can. Follow the instructions on pairing your head unit with the ASWC module. This is specific to the head unit, and instructions are included with the module. Zip tie everything nice and tuck it all away.

On my steering wheel, which is a stock E46 3 series wheel, is mapped like this with ASWC. I believe all buttons are customizable, but you have to jump through some hoops to change the defaults. I left mine default.



It's time for the tablet.

Alright, so this was my biggest challenge. Rich over at MyBimmer.net makes a great bezel, no doubt, but the problem is figuring out how to get the tablet to actually stay on the bezel. He ships it with four angle brackets and screws which do help to a certain degree, but I had trouble getting the screws to sit in the plastic material without coming out again. They are still in my bezel, but serve as more of a guide than something to actually hold the tablet exactly where it's supposed to be.

My first thought was to use hot glue. I figured temperature may be an issue, but I went for it, and it's still using hot glue today. The main issue there, is that it's melting. I live in an area where temperature is anywhere from 25F to 110F at the very hottest and coldest, year round. The car does get very warm, and this eventually caused the tablet to sag in the bezel, not to the point where it wouldn't work, but to the point where I couldn't press the menu buttons on the screen. Not ideal. Here's the hot glue:



It worked for a while but it's not perfect. The solution I think will be to use silicone adhesive. I may be using something like this, but I'm not sure if it's removable (at least easily). We need to find a happy medium between securing it on the bezel and being able to remove it in the future.

This part here will be updated once I make a decision on how I'm going to approach this. Stay tuned!

UPDATE 8/24/14: I have been using silicone adhesive for mounting the tablet for a good 3 months now. No issues, no sag, it's wonderful. No issues with the tablet either!

Before we jump into the tablet software, here's a little overview video of what it can do. I didn't show everything because the video was pretty impromptu, so I apologize for the rambling, but it gives you a pretty good idea of what to expect.

http://youtu.be/9e6gpKpR1nk

The Tablet OS:

Right now I'm running Cyanogenmod 11 nightlies. I've never had any issues with crashing that are caused by CM, all by apps causing crashes. The important thing here is that the tablet gets rooted. In order to have the tablet turn off and on when the car turns off and on, we need to use Tasker. This will let us set up triggers which cause other things to happen. Namely, turning off all necessary radios and such when the tablet loses power, as well as turning off the screen. We need to do the same for turning it on.

Here's a rooting guide for the Nexus 7's. If you're not using one, you'll need to find out how to root.

http://nexus7.wonderhowto.com/how-t...ing-android-4-4-kitkat-windows-guide-0150849/

Once rooted, install Tasker and familiarize yourself. It's an amazing tool. You'll also need Secure Settings in order to wake the tablet. It's a plugin for Tasker. Here are the profiles I use:

on.xml
off.xml

And here's a video I made in regards to Tasker, how it works, and how to import the two profiles I've made. Looking back at this one I'm all over the place but it gets the point across. This is what I get for making videos last minute.

http://youtu.be/szpsDa5YKPg


And that's it! I may have missed something important, as it's late. So read it over if you're interested and tell me what you think!


A couple pictures:

After install:


A couple days ago (blue trim is going in favor of carbon fiber wrap... stoked.)
 

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Discussion Starter · #5 ·
This is how mine looks, just got done this weekend and only cost me about $350 total. I just couldn't do a head unit, they are too slow for me and they don't look good. I used my 1st gen Nexus 7.

Sent from BimmerApp mobile app
Did you guys put a head unit behind the tablet as well, or something else?
 

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Great install, SRP. I just very recently finished up installing a samsung galaxy tab 3 7.0 in my dash. I plan on doing a full write-up in the near future, but thought I would chime in here with a few issues you wrote about.

HVAC Relocation Kit

I had read in other tablet install threads and blogs that the HVAC controls fit well enough in the sunglasses spot without the need for the relocation kit. I found this to be only partially true. As you mentioned, it is not a perfect fit. But I found with some minor modification, it fits almost perfectly. Here is what I did:

First, I took my dremel and cut part of the bracket just a bit. Try putting the HVAC controls in the bracket with the bracket out of the car and you will see why this is necessary.



Then, I cut a spacer out of some wood and glued it on the bracket so that the front of the HVAC controls would line up flush with the front of the bracket. I painted the spacer black after I glued it on. I also glued a few spacers on the top of the HVAC controls.



After making these modification, the HVAC controls sit very snug and line up well with the front of the bracket. I have never had a problem with popping out. I did not want to spend the money on a relocation bracket as my car has over 200k miles and I was trying to do my tablet install as inexpensively as possible.

Tablet Mount to Bezel

I think I came up with a solution better than any others I have seen. Most of the other threads and blogs use thin bent metal strips screwed to the bezel in order to mount the tablet. I did not want to do that because (i) I think that the strips used by most seem flimsy and would have some give when pushed on, and (ii) I wanted my tablet to be easily removable from the bezel. Here is my solution:

I used epoxy to adhere two pieces of wood to the bezel, one on each side of the tablet. Then I cut a piece of wood the length of the tablet (about half an inch thick) which holds the tablet in place via small gate latches. I used a cheap silicon case to protect the tablet and for better grip against the wood.



This setup gives you an amazingly secure tablet-to-bezel installation. My tablet doesn't move a millimeter away from the bezel. While it is latched in there, the tablet and bezel are truly one unit. And the best part - super easy to remove.

Head Unit Location

And finally, you asked about how/where others have located their head unit. Because I was trying to do my install on the cheap, I wanted to use my stock HU so I could keep the steering wheel controls, have radio, etc. I also wanted my install to be reversible. My solution......glovebox:



Took a bit of modification to the back of the glovebox, an Enfig bluetooth adapter, and extending some wires, but I'm happy with the solution.

Hope this helps you to make final modifications to your install. Again, looks great! I think the tablet install is going to become increasingly popular versus the dynavin option.

EDIT: Forgot to mention, I think a backup camera with a tablet install would probably require a bluetooth backup camera option. Otherwise, you are getting into some serious modifying/wiring of the tablet. I think a bluetooth backup camera is about $100-$150.
 

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Discussion Starter · #13 ·
Holy cow, the gate latch and wood idea is perfect. I'll have to see how much clearance behind the tablet I have, but I think I should be ok. I'll try and find a silicone case that doesn't wrap around the nexus too much, so it still sits flush with the bezel.

Awesome ideas, I definitely think I'll be giving your method a try before I start with the silicone. Any chance you could take a few more pictures of the bezel assembly?
 

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Holy cow, the gate latch and wood idea is perfect. I'll have to see how much clearance behind the tablet I have, but I think I should be ok. I'll try and find a silicone case that doesn't wrap around the nexus too much, so it still sits flush with the bezel.

Awesome ideas, I definitely think I'll be giving your method a try before I start with the silicone. Any chance you could take a few more pictures of the bezel assembly?
You bet. I'll take some more pictures tonight and upload them. As for the silicone case, I had to trim parts of the case (on top and on one corner) to get the tablet screen flush against the bezel. My main objective was to make the tablet fit tight while protecting the sides and back.

Also, I didn't buy my bezel from Rich. I really like his bezels, but as I mentioned, I was doing this on the cheap. I was originally going to make a bezel, but found a new e46 aftermarket double din bezel on amazon for $20. However, I've looked a lot at Rich's bezels and the method I used will work the same on Rich's bezels.
 

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Discussion Starter · #15 ·
You bet. I'll take some more pictures tonight and upload them. As for the silicone case, I had to trim parts of the case (on top and on one corner) to get the tablet screen flush against the bezel. My main objective was to make the tablet fit tight while protecting the sides and back.

Also, I didn't buy my bezel from Rich. I really like his bezels, but as I mentioned, I was doing this on the cheap. I was originally going to make a bezel, but found a new e46 aftermarket double din bezel on amazon for $20. However, I've looked a lot at Rich's bezels and the method I used will work the same on Rich's bezels.
Cool, looking forward to it. I'll have to find an easy-to-cut case and go from there. Cheers!
 

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SRP, here are some additional pictures of the system I used to attach my tablet to the bezel. I'll attach thumbnails and you can click on them and blow them up for more details.

It is really a simple concept, I just attached the two wood pieces on each side with some strong epoxy, and then attached the small gate latches to those pieces and the cross piece. You will see that I did have to cut down the edges of the two pieces of wood on the sides of the tablet to make it fit property in the dash.

Also, the screws that came with the latches were too long for the cross piece of wood. I needed to use smaller screws, but the screw holes were too big for the small screws, so I had to drill some small holes in the metal for the smaller screws.

I really like being able to remove the tablet. When I do my write-up, you'll see the release mechanism that I put in to pop out the entire bezel and tablet. Anyway, hope these pictures help.
 

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Great ideas guys. So with a Nexus 7 and probably most tablets, we have the ability to add back up camera, add usb hub to connect more usb options, Bluetooth phone calling, and even FM/internet when in a wifi area?
 
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