nalc's BRZ steering wheel audio control saga

[nalc]

AUGUST 2013 UPDATE: Tested, Impreza SWCs are 100% plug and play compatible with the BRZ head unit

UPDATE JANUIARY 2014: These other threads may be of interest
http://www.ft86club.com/forums/showthread.php?t=39244
http://www.ft86club.com/forums/showthread.php?t=55024
http://www.ft86club.com/forums/showthread.php?t=51941
http://www.ft86club.com/forums/showthread.php?t=15443
http://www.ft86club.com/forums/showthread.php?t=44827


The 2013 Impreza has an option for the same Fujitsu Ten nav head unit as the BRZ. All trim levels of the Impreza use the same SWCs, and all are compatible with the BRZ. The Legacy SWCs look the same, but due to different resistance values, they are not compatible. If you're buying used, not by model, the Legacy ones have a single connector, whereas the Impreza ones have two connectors. The SWCs are sold as an assembly with the cruise control buttons.

There are six wires going to the SWC side of the assembly - Black, Blue, White, and Orange went directly from the connector to the SWCs, and Pink and Purple went from the Cruise control module to the SWCs.

Black, Blue, White, and Orange went to the SWC. Red, Green, Yellow, and Brown went to the CC, and Pink and Purple went between SWC and Cruise Control.

Black is ground for the illumination.
Pink is positive for the illumination.
Purple is another ground (connected to the black wire internally)
Blue is the SWC audio (connect to Pin 21 of the 28-pin harness)
Orange is the SWC phone (connect to Pin 22 of the 28-pin harness)
White is the SWC common (connect to Pin 23 of the 28-pin harness)

____________ ORIGINAL POST (MUCH OF THIS INFO MAY BE INCORRECT, THIS DOCUMENTS THE PROCESS OF FINDING THE ABOVE INFORMATION) ___________

Greetings folks,

I'm one of the many BRZ owners who is somewhat dissatisfied with the touch screen head unit. I'm happy with the way it sounds and looks, and I like HD Radio a lot. I primarily listen to FM/HD radio, and I miss having six preset buttons on the front of the unit like my old LGT. I don't mind not having steering wheel controls (I've never owned a car with them), but I'd really like to have a tactile button to flip through my presets, rather than using the soft buttons. Steering wheel controls would be nice, but not at the expense of replacing the steering wheel (I quite like the BRZ wheel), or doing extremely costly mods.

I'm endeavoring to add physical buttons somewhere in the car to control radio functions.

As I'm sure many of you know, the Fujitsu Ten head unit has native support for steering wheel audio controls. It's available with them in a few other vehicles, such as the 2012+ Impreza.



As a starting point for my modifications, I ordered the SWC module from an Legacy from ebay. This contains two inserts for the steering wheel - the left has the audio controls, the right has cruise control. The same connector is used for both sides, with the base model cars just having the cruise control, and upgraded models having cruise control and SWCs. It looks like it is identical to the Impreza, even though the Legacy has a different head unit. I figure, why would they re-invent the wheel? There were two versions available - one with Vol Up/Down, Seek Next/Last, Mode, and Mute, the other with Vol Up/Down, Seek Next/Last, Mode, Voice Command, Pickup, and Hangup. I bought the one with more buttons since the price was the same, however in retrospect I hardly ever connect my phone to the car, so I don't need the extra phone switches, and I didn't realize before I bought it that it was missing the Mute button, which is something I would use.



I didn't care about cruise control since we already have the little stalk, but I wanted the SWCs.



I got the unit, and took it apart. The module with the buttons unscrews from the silver plastic bezel. This is good, as I will likely paint the bezel black at some point. All of the writing is on the black switches themselves, and is backlit.



The button module itself consists of a plastic piece that the buttons attach to, a PCB, and a backing plate.



At this point, it was time to put my reverse engineering skills to the test. I couldn't find any pinouts or wiring diagrams, so I decided to make one.

The 10-pin connector has 9 pins populated, and one of them is terminated in a spade connector for grounding, so there were really only 8 pins to worry about, plus two wires that went between the SWC and the CC modules, but didn't go into the connector.

Black, Blue, White, and Orange went to the SWC. Red, Green, Yellow, and Brown went to the CC, and Pink and Purple went between SWC and CC.

I noticed that Purple and Black were connected together within the SWC module, and the legs of the LEDs seemed to go to them, so I figured they were ground.

The LEDs in the CC module seemed to connect between red and pink, and the LEDs in the SWC module seemed to connect between pink and black, so my initial guess was that red was the positive for the lighting, and black was the ground for the lighting. I connected it to a variable power supply, and it worked, so good news there. However, I will need to do some investigation to measure the voltage on the pink wire. Unfortunately, it seems that the LEDs in both modules are wired in series, so that at full brightness, the red wire would be +12v, the pink wire would be +6v, and the black wire would be ground, with each cluster of LEDs only seeing 6v. However, I haven't confirmed this yet, and I may be wrong. If I'm not wrong, I will need to retain the PCB for the cruise control module and hide it behind my dashboard, or wire in a potentiometer to drop the power to the LEDs enough that I don't fry them, then adjust it to match the exact brightness of the rest of the interior. I was pleased to note that they are red LEDs, so they will match.



Moving onto the switches themselves, I had another problem to solve. The FT head unit uses a total of three pins for SWC controls - there's a audio controls one, and another one for bluetooth phone controls, and a ground. I had three pins (remember, of the eight, I figured out that two were for lighting, and three went only to the Cruise Control module).

I had blue, orange, and white pins. I connected every combination of pins, and made a table of the resistance values I measured.

No Buttons Pressed: O/B 104.5K, O/W 99.8K, B/W 4.71K
Vol+ : O/B 100K, O/W 99.9K, B/W 89
Vol- : O/B 100K, O/W 99.9K, B/W 193
Seek Up : O/B 100.4K, O/W 99.9K, B/W 603
Seek Down : O/B 100.9K, O/W 99.9K, B/W 1146
Mode : O/B 100.1K, O/W 99.9K, B/W 336
Voice Command : O/B 7.82K, O/W 3.13K, B/W 4.71
Hang Up : O/B 5.71K, O/W 1K, B/W 4.71
Answer : O/B 5.03K, O/W 331, B/W 4.71

So, from this, it was clear that white was the common ground, blue was the audio functions (nominally 4.71K, with the buttons varying from 89 to 1146 ohms), and orange was the phone functions (nominally 99.8K, with the buttons varying from 331 to 3.13K)

This corresponds to the values posted in this NASIOC thread from the subaru shop manual, for the SWC from an '09 Impreza, which look completely different

http://forums.nasioc.com/forums/showthread.php?t=749402

22 Ω - Mute
90 Ω - Volume up
200 Ω - Volume down
360 Ω - Mode
690 Ω - Seek up
1.15k Ω - Seek down

4.7k Ω - Nothing pressed

So, it looks like Subaru uses a standard set of values for SWCs, which should mean that it's possible to swap any of them, as my values are all within the standard 10% tolerance of the shop manual values.

Still left to do:

Make sure they actually work with the FT HU. I'm still guessing, and it's a very educated guess since I've confirmed that my Legacy buttons are identical to the Impreza buttons, and that my Legacy buttons would even work with older Subaru head units that had completely different looking buttons, so I really doubt the Impreza would have the same buttons with different values, but I haven't confirmed completely.

Figure out mounting solution. I will probably trim down the bezel, paint it black, and install it on the dashboard just above the trunk release button, where I can just reach over with my left hand and press it. Will also paint it black if I do that. Seems to be room (I will trim down the upper right corner of the bezel)



Figure out if I can separate the cruise control module without impacting the LEDs in the SWC module.

Find a pin-out of the FT head unit (I know I've seen it a million times but I can't find it in the sticky here or in the sticky on Nasioc) Edit: here it is http://forums.nasioc.com/forums/show...28&postcount=9

1 [NC]
2 Reverse Gear
3 Illumination Dimmer Cancel ("Bright" mode)
4 Mic 5V power supply to mic amp (separate wire)
5 Mic Audio Input + (twisted w/ pin 19)
6 Mic detect (pin tied to chassis ground, not connected to mic module)
7-10 [NC]
11 [NC] (Ground for aux enable)
12 [NC] ("SG" ?)
13 [NC] Aux Video Input (+)
14 [NC] Aux Video Input shield/ground

15 [NC]
16 [NC]
17 VSS
18 [NC]
19 Mic Audio Input - (twisted w/ pin 5)
20 [NC]
21 SWC1 Audio (Seek, Volume)
22 SWC2 Mode & Phone
23 SWC Common
24 [NC]
25 Aux enable
26 Aux audio Right
27 Aux audio shield/ground
28 Aux audio Left

Figure out how to get these wires into the FT head unit. I'll need to extend them which is easy enough to do, but I have no idea what kind of pins I need to crimp on to put in the head unit 28-pin harness.

Figure out where/how to tap in the lighting wires to get it to come on with the rest of the dashboard lights and work on the dimmer.

I will post updates in this thread.

Update: Dire news with regard to this mod. I connected it to the correct pins, but it seems like the FT HU is expecting different resistance values.

I noted the following things - with no buttons pressed, the volume kept going down steadily, even if I turned it up on the knob. Therefore, 4.7K (the no buttons pressed resistance) must be volume down.

I believe Seek Up was Seek Down, and Volume Down was Seek Up.

Next step will now be to find a potentiometer or two and a momentary switch, and start doing it the old fashioned way, sitting in my car with a multimeter recording what different resistances do. I'll start off at maybe 20 ohms just to be sure I don't short anything out, and slowly turn the pot while holding the button down, writing down what the resistance value is everytime it starts to do something different. When I get that, I'll just order the SMD resistors and swap them out for the new values.

If I were to do this again, knowing what I know now, I'd buy the Impreza switch cluster instead of the Legacy. They may look the same, but the Legacy has different resistances.

[nalc]

Update June 19, 2013

I got a 11.26k ohm potentiometer that I had laying around and hooked it up across pins 21 and 23 (SWC Audio and SWC Common)

This is my results

Starting at 11.26K and working down to 22 ohms.

From 11.26K to 6.09K - Nothing happened
From 6.09K to 2.19K - Volume went down
From 2.19K to 529 - Volume went up
From 529 to 100 - Radio tuned down (not seek down, which surprised me)
From 100 to 22 - Radio tuned up

Starting at 22 ohms and working up to 11.26K

From 22 to 436 - Radio tuned up
From 436 to 750 - Radio tuned down
From 750 to 2.17K - Volume went up
From 2.17K to 6.10K - Volume went down
From 6.10K to 11.26K - Nothing happened

Connected between Pin 22 and 23 (SWC Phone and SWC Common)

Nothing happened until I got to the very bottom of the potentiometer range, like 22 ohms, at which point it would mute. I tried shorting it out, and that made it mute too.

I'm unhappy with these results. The stock SWCs are supposed to have seek up and seek down, but I had radio tune, which is annoying. Maybe they're looking for a specific resistance value? I may swallow the bullet and buy Impreza SWCs to see if they work.

Update 6/24:
Found the values on NASIOC:

2011-up Impreza and Forester (both w/ phone/BT buttons): Pin 4: Seek Up 0 Ohms Seek Down 330 Ohms Volume Up 1000 Ohms Volume Down 3110 Ohms No buttons 100K Ohms Pin 13: Mode 0 Ohms On hook 330 Ohms Off hook 1000 Ohms Talk 3110 Ohms No buttons 100K Ohms All models: Pin 14 is the common wire for the SWCs (grounded inside the radio)
I was also told by a member that a short press of the seek button does next preset, but a long press does tune up, so that was the source of my problem. Going ahead with operation "buy new resistors"

[nalc]

Trying to reverse engineer this thing is harder than I expected. Even though it really only needs a few resistors, it has 17 resistors.

R1-R6 are for the LEDs, I didn't measure them
R7 is 68.5
R8 is 112
R9 is 160
R10 is 332
R11 is 820
R12 is 22
R13 is 4710
R14 is 681
R15 is 2200
R16 is 332
R17 is 4.5k

There's also a total of 10 switch pads, despite only having 8 switches, (the voice command and mode switches both push down on two pads each, but only have the metal disc to actually make contact to one of the switch pads). They're just wired in parallel, so no big deal.

I traced out the circuits and figured out what the resistance is.

With no buttons pressed, between blue and white, R = R13 = 4.71K

SW1 (Vol+), R = R12+ R7 (in parallel with R13) = 22 + 68.5 = 90.5 (should be 90 per shop manual)
SW2 (Vol-), R = R12+R7+R8 (in parallel with R13) = 22 + 68.5 + 112 =202.5 (should be 200 per shop manual)
SW3 or SW4 (Mode), R = R12 + R7 + R8 + R9 (in parallel with R13) = 22 + 68.5 + 112 + 160 = 362.5 (should be 360 per shop manual)
SW5 (Seek Up), R = R12 + R7 + R8 + R9 + R10 (in parallel with R13) = 22 + 68.5 + 112 + 160 + 332 = 694.5 (should be 690 per shop manual)
SW6 (Seek Down), R = R12 + R7 + R8 + R9 + R10 + R11 (in parallel with R13) = 22 + 68.5 + 112 + 160 + 820 = 1514.5 (should be 1150 per shop manual)

If you plug in the resistor values I measured above, and compare them to the resistances in post 1 for the commands, that seems to validate my tracing. Everything was spot on except Seek Down which is a bit high, but is probably within range.

This creates a quandry, though. There's no way to swap resistors that it would even be possible to make a higher number switch have a lower resistance than a lower number switch, because the resistors keep adding in series. I can swap values, but from smallest to largest resistance, I'll always need to retain V+, V-, Mode, Seek+, Seek-, whereas the BRZ head unit needs Seek+, Seek-, V+, V-, in that order. So I could get the seek controls to work (which I guess is my real goal) by setting the resistances correctly, but then volume would never be able to work.

My options have narrowed down. I can get the Impreza switches for $125 and just abandon the money I have into this, or I can just get parts bin switches and ditch the nice pretty set of buttons I've got now, or I can break the PCB. I will need to cut the trace at SW3/4 and solder a new trace from SW6 to SW1, which might work.

[nalc]

Ordered the Impreza switches.

[nalc]

Interesting news, everybody!

Turns out that both the Impreza and Legacy switches use the same PCB.

It's marked Niles 156G89.

I measured the resistors as well as the five locations for jumpers. The jumpers are key - they are what allows them to have a common PCB, with traces for both configurations! The issue I talked about earlier is gone.

Legacy Impreza
R1 ? ?
R2 ? ?
R3 ? ?
R4 ? ?
R5 ? ?
R6 ? ?
R7 68.5 681
R8 112 2204
R9 160 N/A
R10 332 N/A
R11 820 331
R12 22 N/A
R13 4710 100600
R14 681 682
R15 2200 2200
R16 332 330
R17 99800 99900
JP1 N/A N/A
JP2 0 N/A
JP3 N/A 0
JP4 N/A 0
JP5 N/A 0

So it looks like by replacing four of the resistors, and removing three, and adding two jumpers while relocating a third, you can turn the Legacy SWCs into Impreza SWCs.

[zoomzoomers]

Good luck with this. I'd like to see how things turn out.

[nalc]

So the next step is to figure out where to mount these. I may end up converting my Legacy SWCs (which I already cut up) and trying to sell my Impreza SWCs (which are still intact), or I may wire it up to have two sets, driver's side and passenger's side, since it looks like it shouldn't be too hard to convert the Legacy SWCs to work with the BRZ.

Here are some pics. I will probably end up retaining the silver fairing and just repainting it, as the buttons look bad without one. Depending on how I need to make it fit, I can trim off some of the flanges to make it smaller.













Any thoughts on mounting? I am leaning towards the right side of the steering column. I have a Limited so there's nothing there besides the blank keyfob cover plate, and that plate seems like a sturdy surface that I could mount the SWCs to. I'll trim the fairing to get rid of that big corner sticking out, and if I do that, I'll probably try to sell the Impreza SWCs and just use the Legacy with the new resistors. Otherwise, I could do to the left of the steering column just above the trunk release, and then use another set on the passenger side. Putting them in the heated switches spot would be nice too, but then I'd need to relocate the heated switches. I was thinking about buying another cubbyhole/USB/Aux piece, and cutting a piece of metal to cover the cubbyhole opening. Then I could put the heated seat switches up there (like a NC miata), and put the SWCs where the heated seat switches used to be. I'll have to do some mock-ups, which I won't be able to do until the weekend after next, although I'll order SM resistors this week to try converting the Legacy SWCs to work. Looks like the ones on there are about 1mm, so hopefully I can find the correct size.

[SkullWorks]

are you aware of the diagnostic screen in the head unit so you can view button functions?

Probably too little too late but if you press all 3 buttons on the HU within a short time period from power up it enters a diagnostic mode and it lets you view SWC functions...may have been options for config too...can't recall ATM...and don't have access to my car currently

I had been intending to do this aswell, surprised to see it wasn't plug and play directly. I thought for sure it would be, I was going to put the buttons on the back of the wheel in the plastic behind the spokes. that way you can use by feel since there is not alot of great options for other placement.

[dlux]

I want physical buttons so bad. Please keep updating!

[nalc]

Originally Posted by dlux

I want physical buttons so bad. Please keep updating!

Well, at this point, it's really just installing it and getting the lighting working. As a high level recap, the 2012+ Impreza SWCs are plug and play. Connect as follows:

Blue wire to HU pin 21 SWC1 Audio (Seek, Volume)
Orange wire to HU pin 22 SWC2 Mode & Phone
White wire to HU pin 23 SWC Common

That will get all of the controls working.

For the lighting,

Black wire to ground
Pink wire to +12v source

I am not sure yet the best spot to tap this into. I'd ideally like to have it light up with the rest of the interior buttons, and I'd like to have the dimmer control it as well, so I need to do some more research there, but the actual getting the buttons to work is done.

What I'm currently working on is trying to get the Legacy SWCs, which work differently than the Impreza ones, working properly. They use a different setup. I bought them first (because they were cheaper and I didn't have the info I have now), and chopped them up for experimenting with, then I bought the Impreza ones. I'd like to get my set of Legacy ones working, because the Impreza ones are completely intact and I'd rather resell them to recoup some of my money instead of just installing them and throwing the Legacy ones in the trash.

[dlux]

I was thinking about an option to locate physical buttons as closely as possible to the shifter. Since that's where my right hand is most of the time, would be nice to just press a button there to "next track", no?

[infanterene]

Yes. steering wheel would be most ergonomic but too difficult to fit. If you piece a kit and harness together I would be interested in buying it.

[dlux]

any update? I've been eagerly awaiting =)

[nalc]

Well, here's my status.

I've ordered some SMD resistors from China to try to convert my Legacy SWCs to Impreza SWCs, and I'm still waiting for them to come in. Otherwise, I'm nearly certain that the Impreza SWCs will be plug-n-play, but I'd rather flip them on ebay as they're completely intact, if I can mod the chopped-up Legacy SWCs to be Impreza SWCs. (For those not following, the new Legacy and Impreza have the same circuit boards and buttons with different resistor networks, the Fujitsu Ten head unit in the BRZ needs the Impreza-style resistor network).

I'm trying to figure out how to insert pins into the 28-pin harness. I'm going to try floppy drive connector pins and the pins from a 3-pin computer fan this weekend - if none of those work, I'm going to carefully measure the existing pins with a caliper and see if I can find something in a catalog that will work.

I'm also mulling over my mounting method. I've got a suction cup camera mount and a suction cup radar detector mount, and I want to rig something up. My current top choice for location is to have them sticking out of the steering column on the right hand side below the wipers. I'll likely just mount the adhesive disk that comes with suction cup mounts on the right side of the steering column, then I'll be able to mod the suction cup mount to have the SWCs, and I'll be able to easily adjust or remove them.

For wiring, I'm going to grab a crappy cat5 wire and use that, as the SWCs have three signal pins, an illumination pin, and a ground, so that will work nicely with the cat5, and I'll wire up an intermediate connector to easy installation and troubleshooting.