Steering wheel controls for BRZ HU - anyone tried Axxess products?
 

Anyone here who, like myself, desperately wants steering wheel controls, and tried OESWC-RF or OESWC-STALK? Successfully or not? :)
In theory it should fit the bill perfectly, considering that the Fuji Ten unit responds well to the same commands as Toyota HU, but I've kind of hit a dead end.

So, after studying the threads and looking at what other people have attempted to get audio controls, I decided that OESWC-RF looked like an affordable solution that was worth trying, so I bought the following:
- OESWC-RF unit, it comes with the steering wheel mounted transmitter and a receiver (a small plastic box with a 12-pin connector).
- Toyota-specific harness (part number OESWC-8113H). In hindsight, I should have bought OESWC-1761H, then I wouldn't need the 10+6 pin harness at all.
- 10+6 pin combined "breakout" harness from SVXdc (I was going to hook up a subwoofer anyway, so it came in handy).
- 28-pin HU harness from autoharnesshouse.

Toyota-specific harness is basically two pass-through harnesses with an additional connector that goes into the RF receiver.
The 12-pin connector is hooked to +12V acc, +12V const and ground (yellow/red/black) wires on one pair of the connectors, and SWC1/SWC2 (white&green and grey/magenta wires) on another pair of the connectors - so 5 wires total.
I was a little surprised to see that the SWC common pin was not connected to the RF receiver at all, and the wire was just a passthrough.
The remaining 3 loose wires on the 12pin connector are designed for the non-RF version, at least according to the manual, so I left them be.

So, I connected 3 power wires to the "breakout" harness, cut SWC1/SWC2 wires (pins 21 and 22) on the 28-pin harness and connected them to appropriate wires leading to the 12 pin connector.
I followed the instructions to the letter - first, you couple the RF transmitter to the receiver; then when you switch the ignition on, the receiver should "detect" the vehicle type -- and I can't get past that point. The LED light on the receiver is blinking rapidly, which, according to the manual, means that it can't detect the OEM stereo type.
What does it expect to get? Besides 3 power there are only 2 SWC wires to be used in a meaningful way to detect the stereo type.
Is it looking for a specific resistance value so it knows it's a "Toyota"? I'm out of ideas at that point...
Feels so close :sigh:
Any help is appreciated!

---
2015 WRB BRZ

The receiver module is essentially an ASWC-1 with an added RF receiver, and probably some custom firmware.

No surprise that their harness skipped connecting to SWC common (28-pin #23) -- the OEM HU gets the same ground from the HU's 10-pin power/speaker harness. You'd only need pin 23 when connecting a real OEM steering wheel with SWCs to the HU (or to an aftermarket interface module).

But I am surprised it needs +12V Battery, when a normal ASWC doesn't. I wonder what they're doing with that? (in what situation would you want the RF SWCs to work while your key (+12V ACC) is off?). The module shouldn't be needing constant power to maintain memory (normal ASWCs don't).

Anyway, try confirming your HU is accepting SWC commands by disconnecting the receiver module and using resistors or a potentiometer to simulate the SWC resistors.
I've done that myself with an FT nav HU out of a 2013 BRZ, so it should work for you.

The module is looking for particular voltages on the wires that connect to the HU. It may also be looking at which pins were used on the 12-pin harness to determine the HU brand (potentially one of several different OEM types -- Toyota, GM, Chrysler, etc.).

I'm wondering if your choosing the OESWC-8113H is throwing off that logic. Download the installation manual for a normal ASWC-1 (PDF link), and compare the harness pin-out in that manual to the 12-pin plug on your 8113H harness.

I haven't had my hands on an OESWC module (and the manual is a bit brief), so I don't know if it has the diagnostic blink codes and manual programming options like a normal ASWC-1.

You'll probably have to call Metra's tech support. I recommend that you verify all of the SWC resistances your OEM HU is looking for first. That will help avoid Metra claiming your BRZ's HU doesn't have SWC capability. They could still claim that the BRZ's differs somehow from other Toyota HUs (but I didn't think that was the case).

Apparently, +12V battery is needed to maintain the pairing between the RF transmitter and receiver - if the power to the module is disconnected, they have to be paired again by pressing "volume up" on the transmitter. I have a feeling that the OESWC is actually a simplified version of ASWC, at least it looks like there is no non-volatile memory in the unit, as all the commands are pre-set and static for all OEM HUs and can be stored in ROM. And there is no usb port (the place where it is supposed to be is glued shut).

When the module gets the +12 acc power, it starts looking for the HU and apparently can't find it. The LED on the module lights up when the buttons on the remote are pressed, but the resistance between ground and any of the SWC pins doesn't change when I press the buttons (it's a poor test, I know - if the unit sends only short commands, they may be too short to be detected by my cheap multimeter). I've checked the resistance between SWC1 and SWC2 on the HU and it was infinity - which leaves me with not too many other things to try.

I'll take a look when I get home and try to simulate specific commands, but I do remember the HU reacting when I shorted one of the SWC pins to the ground (I think it was the "Seek+" command), so at least it is responding.

Judging by the looks, the only difference between Toyota harnesses is that 8113H draws power from a 20pin connector and 1761H from a 10pin connector, the same as the one on the FT HU.
The other pair of 20pin connectors, where the SWC pins are, are identical on both harnesses, and the remaining part with a 12-pin module connector is also the same.

Anyway, thank you for the hints and the encouragement -- at least now I have a plan! :thanks:

PS: Do I understand correctly that ASWC-1 can be manually forced to use a specific set of commands and not try to do the whole "auto-detect" thing with a FT HU? If I won't be able to make the OESWC module work, then at least I will have another option!

I don't know if I'm up to the task, but I would really love to have steering wheel controls for the stock head unit.

You can't try to measure resistance on a circuit that is powered. You could try measuring voltage -- on either the HU's SWC1 or SWC2 pin with respect to ground (test one SWC pin at a time). When the OESWC-RF module is not sending a command, or when nothing is connected, you'll probably see the HU outputting +5V. When the module sends a command, the voltage should drop to something between 0 and 5V (different value for each button).

But if the module is not detecting the HU, it likely won't even try sending commands to the HU.

Yes. Except ASWCs talk to aftermarket HUs. They won't talk to an OEM HU (as far as i know).

On an ASWC, you can also use their app for Android phones to pre-program the module via its USB port (or go back and remap buttons if you decide you want to change something, or change to a different aftermarket HU brand). That lets you skip going through the ASWC's auto-programming sequence in the car.

My plan is to use an Arduino to intercept the cruise control circuit. I haven't worked much on this project but that's the plan...

I only really need preset up, preset down, and mute. I'm planning to use the same 28-pin jumper harness to avoid hacking up the stock wiring and a similar one for the cruise control connector.

Made some progress - I think I'm getting closer:

- HU is indeed responding to commands, although the unit is, well, not particularly fast, so very brief shorts to the ground (which are "Seek+" and "Mode" for SWC1 and SWC2 respectively) do not register at all.
- in the "auto-detection" mode, it looks like OESWC module in the beginning of each ~20-second cycle sends (very briefly) voltage sequences to SWC1/SWC2 pins. Even my friend's pro-level multimeter was not quick enough, and I don't think I'm ready to invest in an oscilloscope :)
- According to Toyota specs, the normal voltage between SWC1 and ground, and between SWC2 and ground should be in the 4.5-5.5 volts range. The voltage on both SWC1 and SWC2 pins is 3.4 volts, so I tapped 5 volts from an old cell phone USB charger to both SWC pins (disconnecting them from the HU first, just in case).
The good news: the module immediately went into the "detected" phase, so it does look like it expects a specific voltage on SWC pins.
The not so good news is that apparently the detected stereo type was not correct - any button press (doesn't matter if it's short or long) would send what looks like a digital sequence to the SWC1 pin, and nothing to the SWC2 pin.

My next steps are:
1) Looks like Nissan's stereos have 3.3 volts on SWC pins from the HU - I'm trying to get hold of a high-res picture of their Nissan-specific harness to see what two pins on the OESWC connector are wired for the SWCs, there's a chance those are different pins and maybe it's just a question of using the right one;
2) try to get a hold of either a variable voltage power supply, or just a couple of potentiometers to simulate different voltages and see if I strike gold - my friend's Solara didn't even have pins for SWCs, so there's nothing I could measure.

There's still a chance that the HU won't understand a single command OESWC will generate no matter what mode I'll be able to trick it into; in this case, it's cheaper for me (both cost-wise and time-wise) to just replace the HU - the OEM is not THAT great :)

I just realized that I never posted an update -- long story short, the stock HU is just too slow to recognize the commands given by OESWC-RF, but it works just fine with hard-wired switches... except that I wanted a slightly more elegant solution. Replacing the HU it is, but it was still worth a shot.

@SVXdc im working on this and got a harness set up with almost all working. for some reason i can't get mode/talk features to work even tho everything else works fine (2014 bra radio) any ideas on why only these 2 features wouldn't be working?