Sony XAV-AX200 Install with OEM Rear Camera and Steering Wheel Ctrl Retention

I'm posting this mainly because I couldn't find any write-ups on retaining the OEM steering wheel controls on the cheap (without buying some extra module). I'm also comparing the Metra and Scosche dash kits since I found that there are pros and cons to each one. Without further adieu -- here's the install of a Sony XAV-AX200 Android Auto head unit into a second gen (2015 specifically) Tacoma, without losing any of the factory features.

Parts
First, an itemized parts list with estimated costs and where I bought em.
[Source unit] Sony XAV-AX200 - $338 (Frys promo)
[Primary Harness Adapter] Metra 70-1761 - $3 (Amazon)
[OEM USB Port Adapter] Axxess AX-TOYUSB - $9 (Amazon)
[OEM Camera Harness] Axxess AX-TOYCAM3 - $14 (eBay | SonicElectronix)
[Dash Kit Option 1] Metra 95-8235CHG - $26 (Amazon)
[Dash Kit Option 2] Scosche TA2111BPB - $41 (Amazon)
[OEM Steering Wheel Control Harness | OPTIONAL] Axxess AX-TOY28SWC - $9 (Amazon)

You can get by without all the extra harnesses, but having them makes everything "plug and play".

OEM Steering Wheel Control Function
First order of business... reverse engineering the steering wheel controls.

The factory schematic shows there are four wires SW1, SW2, SW3, and SWG. After a few minutes with that print out and a multimeter I found that the buttons were pretty much divided into three sets of four identical signals with reference to SWG:

Up|Mode|Enter - ~1.5Ω (or short effectively)
Down|Phone End|Back - 330Ω
Vol+|Phone Answer|Right - 1kΩ
Vol-|Voice|Left - 3.1kΩ

The mapping between buttons and wires is as follows:
SW1 - Violet/White, Pin 21 - Up, Down, Vol+, Vol-
SW2 - Yellow/Black, Pin 22 - Mode, Voice, Answer, End Call
SW3 - Black, Pin 24 - Enter, Back, Right, Left
SWG - White/Red, Pin 23 - Ground Reference

So twelve buttons, delivered across three wires... but this Sony source unit (and a lot of others) only has TWO wire inputs for the steering wheel controls as evident by the XAV-65 accessory cable.

In practice, connecting only two wires will work, but you'll have four buttons that don't work. The Sony support instructions for the aforementioned cable don't bother mentioning this, but the wires they state to connect to will still allow the volume and Bluetooth buttons to work -- which is fine if you're okay with that, but I wanted Left and Right to work for track backward and forward respectively.

This Sony source unit allows you to assign your own mapping between function and steering wheel button through a learning process that basically just figures out the differences in voltage on the two steering wheel input lines when each button is pressed. For example, button1 could be 2V, button3 could be 3.5V -- this is how the buttons are able to share a single wire. I'm not sure what sort of precision the Sony is capable of doing (i.e. how big of a difference it needs to see to accurately discern one voltage from another -- 1.1V vs 1.3V for example), but I was hoping it would be good enough for me to just slightly change what one of the OEM control wires puts out and join it with another.

Three wires to two
I had a few miscellaneous resistor values lying around so after some rough math to see what could work from what I had, I settled on a 6.9kΩ resistor that I would add to one of the OEM signal wires to effectively change its signal output just enough to be different from the other wire it was going to be sharing a path with. I inserted this resistor between the SW1 wire and the SW3 wire and ended up running the SW3 wire to Input 1 of the Sony steering wheel controls and SW2 to Input 2. I grounded SWG and did nothing with the shielded/ground wire in the 3.5mm cable. Here's a rough schematic to what that looked like:

Code:

OEM Connector         3.5mm to Sony
SW1--|
     0 <-- 6.9kΩ resistor
SW3--|--------------- Input 1
SW2 ----------------- Input 2
SWG ---Ground     x-- Ground (not used)          

This little hack allowed the Sony to now "see" four buttons on one wire, and six buttons on the other. Yes, six isn't eight... While this trick wasn't enough to get all twelve buttons working, it was enough to get ten of them working, which is fine by me because the Sony only has ten programmable button functions.

The unused buttons were Up and Down. One of them could be programmed, but the other was too close in value still to another button, I forget which one though ¯\_(ツ)_/¯.

I ended up mapping everything as follows:

Code:

OEM Button      Sony Function
Up ------------ N/A
Down ---------- N/A
Left ---------- Track Back
Right --------- Track Forward
Enter --------- Play/Pause
Vol+ ---------- Vol Up
Vol- ---------- Vol Down
Mode ---------- ATT
Back ---------- Source
Answer -------- Answer
End Call ------ End Call
Voice --------- Voice

Notes on Axxess AX-TOY28SWC
I decided to use this harness to make everything 100% plug and play. This harness is intended to be used with the Axxess ASWC-1 universal steering wheel control interface module, but I just wanted it for the OEM connector. Plus, along with giving you access to all four of the OEM steering wheel control wires, it also gives you access to the parking brake and reverse signal wires, and provides a 3.5mm connector that you can use.

Alternatively, you can save money and just cut up a 3.5mm cable and use the left and right audio signal wires as your "Input 1" and "Input 2" wires, it doesn't matter which one is which since you'll be using the learning feature of the radio.

Bonus -- Metra vs Scosche dash kits
I have to admit that first I purchased the Metra kit because it was cheaper, I'm cheap. However, after installing it, I found that the radio was far too recessed for my liking. The OEM radio sticks out from it's respective bezel a bit, and this one was recessed so it felt extra weird.

So I sucked it up ordered the Scosche kit. The Scosche kit is nice because it comes with metal brackets that fit way better than the Metra's plastic ones AND the radio doesn't seem to end up as recessed and appears to sit at a different angle for whatever that's worth to you.

Unfortunately, I found neither kit 100% satisfactory. The Metra bezel seemed to fit the dash better, it sat more flush along every side, and I liked that it had a matte trim around the hazard switch assembly like the OEM bezel. The Scosche definitely had a better position for the screen in the end IMO, but suffered from not as nice of a fit to the rest of the dash and had a painted hazard switch assembly trim that was all one piece with the bezel. The hazard button also appears to stick out further with the Scosche kit. Oh and the volume knob is really close the left most wall, but meh (good thing we went through all that trouble for the steering wheel controls right?).

Here are the comparison pics of both options.

Head on shots
Notice the sides of the Metra kit and how much more "flush" it fits as well as how much more pronounced those bevels are on the edges.
Metra

Scosche
You can really tell at the top how it is not as flush with the rest of the dash as the Metra. The sides were about the same and also notice how less aggressive the bevels on the sides are.


Driver's seat shots
Metra

Scosche


I think I'l honestly just try to design and 3D print something for the factory bezel to fill the gap between the OEM screen cutout and the new screen and try to reuse that instead. If the Metra kit had the radio sit just a bit more forward it would have been satisfactory to me, oh well.

 

Not getting much action here but I just wanted to thank you for the awesome write-up. I plan to install an xav-ax100 soon and this post will save me a lot of time and money. Thank you!!

Did the steering wheel control cable (aux looking plug) come with the head unit?

 

Thanks. If you buy the

$15 Axxess AX-TOY28SWC Steering Wheel Controller Add-On Harness with RCA and 28-Pin Connector for Toyota Vehicles

Axxess AX-TOY28SWC it comes with one you can jump together with the other steering wheel control wires on the same harness, or you can just cut up a stereo 3.5mm aux cable and just use the left and right audio signal wires as the steering wheel control 1 & 2 wires.

 

I didn’t read through the novel you posted but when I did my pioneer H/U, I got the module to retain steering controls and had no issues. To me, with it all being plug and play, it was worth it.

The pics look good!

 

One more question before I order this stuff. Isn't the factory backup camera 6 volts? Did you do anything special there? Reason I ask is I see the

$25 AX-Toycam3 Axxess Toyota 2013-2016 Back-Up Camera Retain/Add-On

AX-Toycam3 in a 6 volt version and am confused if I need that one. Thanks!

 

Oh man, I did do something for it and I can't believe I forgot to talk about it!

I ordered these (6pk adjustable DC-DC buck converter) and dialed it down to 6V. I wired the input side to ACC (switched 12V) and ground and the output side to the camera's power and ground on the AX-TOYCAM3 harness. I also put some heat shrink over it to keep it kinda "protected", but electrical tape or a hobby box would have probably been just as fine.

You could buy the AX-TOYCAM3 in a version that comes with a converter ready to go, but I was trying to be as cheap as possible, plus I'm handy with a soldering iron.

 

Awesome, thanks for the quick reply. Think I will do something similar with a DC stepdown regulator.

 

Just a follow-up on how my install went, and a warning for anyone else like me who has a factory JBL. These directions WILL NOT work for you. How do I know you ask, well I spent a good portion of the day yesterday soldering everything up, then went out to car to plug in and nothing mated (except steering wheel control plug). Apparently the non-JBL systems are wired very differently. So in the end I had to buy the PAC converter (which also does the steering wheel controls).

This is not meant as a put-down to dome's awesome write-up, I should have done more research. If anyone with non-JBL is looking to do this, I have all the harness's sitting around and will sell cheap!

 

Ah yeah, sorry I should have called out non-JBL!

 

Thanks a lot for this post!! I followed along and coincidentally had already purchased the xav-ax200 myself - you instructions were spot on.

I bought the truck knowing I would eventually replace the head unit, based on how the stock stereo looked. Definitely do not want a new aftermarket stereo to stick out like a sore thumb.

I tried to be ultra cheap, and think i have succeeded. I used "cintra board" to utilize the stock stereo bezel and not have to buy a new one that I was not happy with. That and the texture of this stuff looks very good against the stereo.



It took over an hour of trimming to fit the stock bezel, but it even wedges in without the need for glue etc.



Once I made that, I popped it back out and traced my double din size level so that the stereo would sit dead smack int he center of the bezel.



Once i got the radio to fit in the cintra board, i just used 2 of the stock screws to screw this stereo into the stock brackets and it worked perfectly! 1 screw per side from the stock bracket into the aftermarket stereo.



It is not perfect, but for it being free and getting close to perfectly what I was looking for, I cannot complain.

 

Nice! I eventually want to reuse the stock bezel, the fit is just way better.