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Old 06-19-2013, 05:54 PM   #1
nalc
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Member#: 242761
Join Date: Mar 2010
Location: Delaware County, PA
Vehicle:
2013 BRZ Limited 6MT
Galaxy Blue Silica

Default SWC resistance values for Fujitsu Ten nav HU?

Hi folks,

I'm trying to add SWC to the FT HU in my BRZ.

It appears that the FT uses different resistance values than the standard Subaru one.

For reference, this is the normal resistance values

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

This is taken from a '09 Impreza. I bought the SWCs from a 2012+ Legacy, and I've confirmed that they are the same values.

However, when I connected them to the pins on my Fujitsu Ten head unit, it didn't work. Namely, even with nothing pressed, the FT volume decreased.

I decided to try to figure it out. I had a potentiometer around that I measured 22 ohms minimum value, 11.26K ohms maximum value. I connected the pins and noted the following

Connecting at Pin 21 and 23 (SWC Audio and SWC Common) 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

So, overall, it looks like 22-100 ohms for radio tune up, 436-529 ohms radio tune down, 750 to 2.17K ohms volume up, 2.19K ohms to 6.09K ohms volume down, based on the minimum and maximum values I measured.

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.

Has anyone with a 2012-2013 Impreza with the FT nav unit measured the SWC resistance values? I'm at a loss trying to get mode switch to work, and I don't know why my radio is tuning up and down rather than doing next or last preset (can that be configured somewhere?)
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Old 06-24-2013, 07:31 AM   #2
SVXdc
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Join Date: Oct 2002
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1996 SVX L AWD
Laguna Blue Pearl

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Thanks for taking those measurements!

The BRZ FT nav is looking for the same values that Subaru uses in 2011-up models (with HUs with built-in USB and Bluetooth). See the 2011-up tables in this post. I've been told that Toyotas use those same values.

The tune up/down buttons actually do next/previous preset (when you press briefly), or seek up/down (when you hold longer). So the SWC buttons are a combination of the HU's four on-screen tuning buttons.

0 ohms between pins 21 and 23 does tune/seek up.

0 ohms between pins 22 and 23 does mode, not mute. I'm guessing you didn't notice that yours switched to aux (with nothing playing), making you think that was mute.

I verified all of that on a BRZ FT nav that I bought for testing.

I could not get the phone/BT functions to work, even after registering two different phones. Some of the on-screen phone function buttons were grayed out, so the HU was unhappy about something..

If you're still looking for pins to add to your car's factory 28-pin harness, I'll e-mail you about that as soon as I can.
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Old 06-24-2013, 03:52 PM   #3
nalc
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Fantastic info, thanks for the response.

I'm not sure if you're a general Subaru guru or just an Impreza guru, but this may be of interest for you.

The 2012-2013 Legacy has SWCs that look the same as the Impreza, but have different resistance values. They use a 3-pin configuration that has the same resistance values as the 2008 Impreza for the Audio, and the same resistance values as the 2011 Impreza for Phone. So it's essentially the "old" 4.7K resistance combination for Vol Up/Down, Seek Up/Down, and Mode, and Mute (although the Legacy SWCs that have the phone commands remove mute, and replace it with the Voice Command), and the "new" 100K resistance combination for the SWC phone controls.

I posted this to FT86Club two weeks ago but nobody seemed to give half a crap about it. Maybe the info will be of interest to you.

Quote:
Originally Posted by nalc View Post
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. Red in the 10-pin connector was the positive for the LEDs.

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)
I'm going to try replacing the surface mount resistors (if I hadn't already chopped up the wiring, I'd try to sell the Legacy SWCs and just buy Impreza SWCs, but I'm past that now) to get the Legacy SWCs to work with the FT HU. I'll post the results of that here. There's an ebay seller with Legacy SWCs for $49, which sure beats the $126 that subaruparts.com has for Impreza SWCs, so swapping resistors works, I'll be a happy camper.

And yes, I'm definitely still interested in buying extra pins to try to add this to the harness properly. Luckily, the 28-pin doesn't seem to provide and sound-essential functions, mostly just the mic and aux input, so I've been testing this with spare pins from the SWC 10-pin connector, which fit around the FT pins (but don't fit into the 28-pin connector), just pressed onto the relevant pins with the 28-pin connector removed.

I was pretty confused and enraged that it was tuning the radio up and down instead of just going to the next or previous preset, and I was hoping that it was just an issue of leaving the pin connected for too long, but thank you for anticipating my question and confirming it for me. I feel a lot better going off of the 'official' values instead of just arbitrarily picking somewhere in the middle of the range I measured.

I think it may have been mute on mine. I will double check next time I have it apart, but I definitely remember connecting it and having the sound go away, then disconnecting it and turning the volume up to go back to what I was playing before, I don't recall ever having to go back to my original source on the touchscreen. Or maybe a long press is mute? I will investigate it.

Last edited by nalc; 06-24-2013 at 03:58 PM.
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Old 06-27-2013, 06:25 AM   #4
SVXdc
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Laguna Blue Pearl

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I'm interested in all Subarus (fairly modern ones, at least). I did have the info for all of the different models' wheels. I just need to update my HU FAQ thread.

I checked, and you're right -- holding the MODE button does toggle into and out of mute. Now that I think about it, I vaguely recall reading about that somewhere (perhaps one of the model's owner's manuals).
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Old 06-27-2013, 09:20 AM   #5
nalc
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Member#: 242761
Join Date: Mar 2010
Location: Delaware County, PA
Vehicle:
2013 BRZ Limited 6MT
Galaxy Blue Silica

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Quote:
Originally Posted by SVXdc View Post
I'm interested in all Subarus (fairly modern ones, at least). I did have the info for all of the different models' wheels. I just need to update my HU FAQ thread.

I checked, and you're right -- holding the MODE button does toggle into and out of mute. Now that I think about it, I vaguely recall reading about that somewhere (perhaps one of the model's owner's manuals).
Pfft, owner's manual? That's for people who don't own a good multimeter and a potentiometer (Although I've only got a Craftsman, not a Fluke)
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Old 07-03-2013, 09:45 AM   #6
nalc
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Join Date: Mar 2010
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2013 BRZ Limited 6MT
Galaxy Blue Silica

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So I've confirmed that there is no remotely easy way to get Impreza SWCs to work in the Legacy, or vice-versa.

Essentially, they are wired with a bunch of resistors in series, with switches between each one to short it to the ground. So if you press the lowest resistance button, it closes the circuit with the first resistor, if you press the second lowest resistance button, it closes the circuit with the first and second resistor in series, if you press the third lowest resistance button, it closes the circuit with the first and second and third resistor in series.

What this means is that even if you are willing to replace the surface-mount resistors, it still won't work, because the switch functions are in a different order.

Looking at the PCB for the Legacy controls, there are 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

I looked at the traces to see how each switch completes the circuit.

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) - The Legacy controls with phone buttons replace the Mute with the voice command, so I assume that the variant with the regular Mute button would connect only R12 for mute.
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.

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 thatorder. To make it work, you'd need to either remake the PCB, or carefully cut the traces and reconnect them so that Volume is after Seek, and then move Mode over to the other pin. So it goes from a 20 minute job of just swapping out resistors to a risky and more involved job. There's absolutely no room to run even thin wires to replace the cut traces, so you'd need to start modifying the plastic backplate that holds it together to get things to fit, which could easily turn into a disaster.
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Old 08-09-2013, 03:20 PM   #7
nalc
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Join Date: Mar 2010
Location: Delaware County, PA
Vehicle:
2013 BRZ Limited 6MT
Galaxy Blue Silica

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Actually unconfirmed. They are the same PCB for the Legacy and Impreza, just different resistors. The traces are set up so that using jumpers, you can have either configuration, so you just need to replace the jumpers and replace a couple of resistors.

I have the info if anyone is interested.

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