[Nexus 7 Accessories] michaelsteinbach:
So I've replaced my stock Navigation system in my '09 Mazda 6 with a 2nd gen Nexus 7.

I bought a used one off ebay because it didn't matter to me if the case/cover was banged up or not as I was planning on building it into the dash. The Nexus fits pretty well in the 2-din opening of the aftermarket panel I got [American International brand kit# MAZK860]. I used a Minisuit-X TPU case to help hold the tablet in place. The case creates a raised frame around the screen and makes it easier to locate the screen from the back of the 2-din panel. Notches needed to be cut in the sub-frame piece of the din kit for the USB connector and headphone jack, but other than that very little modifications were needed. I used a piece of PVC perforated sheet to hold the tablet into the din plate. The perforations in the sheet made it easy to cut out notches and holes with side cutters and achieve the shape I wanted without having to make a mess using a dremel.

For audio, I had purchased a Syba SD-CM-UAUD DAC but had trouble getting it to work right so I am now just using a 3.5mm 4-pin splitter to 3.5mm headphone/mic jacks. I have a JK MIC-J 044 lapel clip microphone stashed behind a small vent in the upper console panel and wired a headphone jack into the harness [Metra 70-7903]. I know some people think the DAC is far superior but I found the headphone jack audio output good enough for me and running it through the stock Bose amplifier in my car sounds excellent.

I'm also using a Joycon EXR to capture steering wheel controls and an EasyCap Dc60 to capture video from my KS1 dual channel dash camera. The camera is set to show the rear view for the video out so I can use it as a back-up camera on the tablet.

My first time installing the tablet worked ok. I had a few problems including the steering controls not working (except Volume down) and the battery wouldn't stay charged enough, forcing me to remove the tablet and charge it every other week. The Easycam also wouldn't work and flash drives wouldn't load right. The Joycon, Easycap, and flash drive issues were due to the $2 4-port hub I got free with something. I tried an Amazon Essentials hub too and it had an intermittent short. A 4-port Insignia hub from Bestbuy did the trick and everything is working now.

I did rebuild the harness last weekend because I wanted to get the Li-Ion battery out of the hot dash. Even though this setup was working ok, when it's 90-plug degrees outside, the tablet will shut itself off and boot-loop until it cools down. I decided to replace the battery with a 12V to 4.2V DC Step-Down regulator. I got an extra battery from ebay and remove the tiny controller board. I had read where other people just replaced the battery with a power supply and were getting odd messages from the tablet about how it was at 0 volts and wouldn't sleep or update properly. So, I used the battery control board and it reports the battery level to the tablet (usually around 90~95%).

The only issue I am having with the power is that when I start the engine, either the power is dropping too much or the car kills power to the radio harness and then I have to wait for the tablet to restart.

To fix this, I plan on using a capacitor to try and keep the tablet powered while the car is starting.

I do need some help. Though I have removed the Li-Ion battery, the overheated tablet will still shut down and boot-loop until it cools down. Is there a way to program it to ignore the temp. sensor? If not, does anyone know where this particular sensor is so I can replace it with a fixed resistor and make it think it's always room temp?

Questions, comments, and ideas welcome!

~Mike