Axxess ASWC Steering Wheel Interface Module
Installation with Subaru 20-pin Harness

Axxess ASWC module picture

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Connecting 20-pin Harness To HU's Harness

Read and understand all of the connections before starting.  You will be joining the +12V and ground wires from several different harnesses (my 20-pin, your HU's, ASWC, and possibly other accessories).

See this guide for connecting my 20-pin Subaru installation harness to your HU's power/speaker harness.

Connecting the ASWC Module

Refer to my pin-out table for Subaru's 20-pin harness.  Column "A" shows the wires on the 20-pin harness.

Ignore the printed "Application Chart" booklet that was included in the ASWC package — some versions of the booklet have incorrect diagrams and/or pin information for the factory harnesses in Subarus.

Also ignore where the ASWC vehicle-specific docs talk about connecting to your Subaru's factory wires.  You will use the two or three SWC wires on my harness (which are BROWN/RED, BROWN/BLUE, and BROWN/BLACK).

Connecting the ASWC to the Car

Join the following wires between the ASWC's harness and my 20-pin harness.  Where colors are listed as a pair, the first is the main color and the second is the color of the stripe(s) — MAIN/STRIPE.  The stripe(s) are usually thinner.


SWC Variation "A" — Subaru models that do not have phone/BT buttons (only 6 audio buttons):

  1. ASWC's RED wire to the other RED wires (my harness' and your HU's)
  2. ASWC's BLACK wire to the other BLACK ground wires (my harness' and your HU's)
  3. BROWN/BLACK wire on my 20-pin harness (pin 14) to the other BLACK ground wires (same as above)
  4. ASWC's WHITE/GREEN wire to the other ground wires (same as above)
  5. ASWC's GRAY/RED wire to the BROWN/RED wire on my 20-pin harness (pin 4)

Note: If you have either the OEM Kenwood or TomTom navigation HU, I also build a 24-pin harness that will allow you to connect to your car's SWC wires without splicing into the factory wires.  E-mail me for details.

Subaru 2008–up Impreza/Forester, 2005–2007 Legacy/Outback audio-only SWCs
2008–up Impreza, Forester

Subaru 2010–up Legacy Outback audio-only SWCs
2010–up Legacy, Outback
(click to see larger images)

SWC Variation "B" — 2011–up Impreza and Forester with phone/BT buttons (On/Off-Hook and Talk):

  1. ASWC's RED wire to the other RED wires (my harness' and your HU's)
  2. ASWC's BLACK wire to the other BLACK ground wires (my harness' and your HU's)
  3. BROWN/BLACK wire on my 20-pin harness (pin 14) to the other BLACK ground wires (same as above)
  4. ASWC's GREEN/ORANGE wire to the BROWN/RED wire on my 20-pin harness (pin 4)
  5. ASWC's BLACK/GREEN wire to the BROWN/BLUE wire on my 20-pin harness (pin 13)

Do not ground any of the ASWC's other wires.

Note: The ASWC's harness originally had both GREEN/ORANGE and ORANGE/GREEN wires.  Several people have used the wrong wire, so look closely at yours.  The stripes are thinner than the main color.  On the GREEN/ORANGE, the orange was pale (somewhat washed out).
2011–up WRX, STI, Forester
2011 Impreza
w/ Bluetooth
Subaru 2011 Impreza/Forester w/ BT - audio SWCs
Audio buttons
Subaru 2011 Impreza/Forester w/ BT - phone SWCs
Phone buttons
(click to see larger images)
2012–up Impreza & Crosstrek w/ Bluetooth
2014–up Forester w/ Bluetooth
Subaru 2010–2011 Legacy Outback audio+phone SWCs

SWC Variation "C" — 2010–up Legacy/Liberty/Outback with phone/BT buttons (On/Off-Hook and Talk):

Note: Your ASWC module must have firmware dated July 19, 2010 or later.

  1. ASWC's RED wire to the other RED wires (my harness' and your HU's)
  2. ASWC's BLACK wire to the other BLACK ground wires (my harness' and your HU's)
  3. BROWN/BLACK wire on my 20-pin harness (pin 14) to the other BLACK ground wires (same as above)
  4. ASWC's WHITE/GREEN wire to the other BLACK ground wires (same as above)
  5. ASWC's GRAY/RED wire to the BROWN/RED wire on my 20-pin harness (pin 4)
  6. ASWC's GRAY/BLUE wire to the BROWN/BLUE wire on my 20-pin harness (pin 11, or pin 13 on some 2012–up models)
Subaru 2010–2011 Legacy Outback audio+phone SWCs
2010–up Legacy, Outback w/ BT
(click to see larger image)

All Subarus:

The ASWC's 12-pin harness will have many "leftover" wires that you won't use.  Individually insulate all of those unused wires on the ASWC's harness.  Don't cut off any wires — you may need them if you want to re-install the module in another make/model car later.

Note: The pink wire on the ASWC harness may be labeled "MUTE".  Ignore that label — this wire has nothing to do with muting (Metra's harness subcontractor used pink wire labeled for radio harnesses).  Do not connect anything to that wire.

Connecting the ASWC to your Head Unit

Most HUs have a 3.5mm jack for a wired remote control (usually labeled "W/R", "SWC", or similar).  For those, simply plug in the ASWC's right-angle 3.5mm plug.  Your HU may have additional jacks for an aux input or other A/V inputs or outputs.  Those are not for steering wheel wheel controls.  Refer to your HU's installation instructions to determine which is the correct jack.

Eclipse, Kenwood, and some recent JVC HUs have plain wire(s) instead of a 3.5mm jack.  For those, you will use the 3.5mm jack adapter that was included in the ASWC package.  Follow the directions in the ASWC's instructions for connecting the ASWC adapter's wires to your HU's SWC wire(s).

Metra recently started including a tiny 12K ohm resistor in each ASWC package.  I insert that inside the plastic bag with the ASWC's female 3.5mm adapter.  If you purchased your ASWC from someone else, you may find that resistor loose in the package or inside the instruction manual or warranty card.  See my notes about the resistor, below.

Tip: If you don't need the ASWC's 3.5mm jack adapter for your install, save it (along with the resistor) in case you later switch to a Kenwood, JVC, or Eclipse HU.  I suggest wire-tying it to the ASWC or its harness, to store it behind your HU.

Tip: It's possible to manually remap using just your SWC buttons.  This is much easier to do if you locate the ASWC so that you can still see its LED even after you have closed up your dash.  Even better if you position the ASWC so that you can reach its reset button.

Kenwood and some JVC HUs

Instead of a 3.5mm jack, Kenwoods and some recent JVCs have a single wire for "Steering Remote Control" on the power/speaker harness (normally LIGHT BLUE/YELLOW — check your HU's installation manual to verify the color!).  Connect as follows:

  1. Kenwood/JVC's BLUE/YELLOW SWC wire to the ASWC 3.5mm jack adapter's Brown wire
  2. Insulate the ASWC 3.5mm jack adapter's BROWN/WHITE wire
  3. Plug the ASWC's 3.5mm plug into the 3.5mm adapter's jack

Eclipse HUs

Instead of a 3.5mm jack, Eclipse HUs have two or more individual wires.  These wires may be part of the power/speaker harness, or on one of the additional harnesses that plug into the rear of the HU.  The opposite end of the SWC wires may terminate into a white, rectangular, 20-pin socket.

Some Eclipse HUs use BROWN and BROWN/BLACK wires.  If your Eclipse uses those colors for its SWC wires, connect as follows:

  1. Eclipse's BROWN wire to the ASWC 3.5mm adapter's BROWN wire
  2. Eclipse's BROWN/BLACK wire to the 3.5mm jack adapter's BROWN/WHITE wire.

Other Eclipse HUs use wires colored BROWN, WHITE, and BLACK.  If your Eclipse uses those colors for its SWC wires, connect as follows:

  1. Eclipse's BROWN wire to the ASWC 3.5mm adapter's BROWN wire
Eclipse's WHITE wire to the 3.5mm jack adapter's BROWN/WHITE wire.

If the HU does not recognize all of the car's SWC buttons, try reversing these two wires.

If your Eclipse HU has different SWC wire colors, and the HU's installation manual does not identify them, you will need to contact Eclipse and/or Metra's technical support for guidance.

Programming the ASWC

The ASWC will automatically detect the Subaru's wheel buttons.  You do not need to press a Subaru's Volume Up button during detection.  In most cases, the ASWC will also automatically recognize your HU.  Simply follow the ASWC's normal procedure for auto programming.

Ignore where the ASWC's manual refers to its LED color.  One of the enhancements for the ASWC-1 was changing to a bi-color LED (RED/GREEN), but there may still be places in the manual where the manual says RED when it should now say GREEN.

On some HU brands (Pioneer, Clarion, and possibly others), the ASWC's automatic programming will assign the car's phone buttons to do audio functions — preset up, preset down, and mute.  This is because most HU models in those brands do not support any phone/Bluetooth functions.  If this happens with your HU and you think the HU might support the phone commands, you will need to program those buttons yourself.

Note: Very few Pioneer models support a command for "Push To Talk" or "Voice Recognition."  And according to Kenwood, the only phone-related remote command their HUs accept is "answer call" (you can use the MODE button to end a call).

Recent Firmware Updates

  • In an April 2012 update, Metra added a shortcut step to program the phone functions:  After the ASWC completes its auto programming (and after it gives the LED blink codes to confirm which wires and which HU brand are connected), the LED will go solid ON.  Press and hold your wheel's on-hook button until the LED turns off (should take about 4 seconds).  That should program all 3 phone/BT buttons.  Test to make sure all 8 buttons work.  See ASWC's vehicle-specific guide (online) for more details about the shortcut.
  • In an update released May 13, 2013 (V 3.13) Metra added the ability to dual-assign steering wheel buttons (programming different functions for short and long SWC button presses).  See the latest version of the ASWC-1 Installation Manual for details.
  • On June 11, 2013, Metra released an update (v 3.15).  The release notes include the comment: "Fixed MODE button not working on some Pioneer radios.  Only affects 257291 Rev E boards."

If you purchased your ASWC from someone else (or got one from me prior to those dates), you should update your firmware.

Phone/Bluetooth buttons not working

On cars with phone/Bluetooth SWC buttons, the ASWC module will definitely "see" all 8 of your car's SWC buttons (including the phone/Bluetooth buttons).  You can program the module to assign each button to any remote command that your HU supports.

That last part is key: Many HUs don't have remote control commands that correspond to all of your wheel's phone buttons (even HUs that have built-in BT).  This is usually a limitation of the HU itself, not the interface module.  HUs where the BT function is provided by an external accessory unit have been especially bad about not recognizing those remote commands.  You can program the ASWC to assign any leftover buttons to do additional audio functions (e.g., Mute, Band, Seek Up, etc.), so none of the buttons need be "dead."

If the ASWC's automatic programming appears to leave the phone buttons (or any of the others) unassigned, first check your wiring (see the "troubleshooting" tips in the ASWC's manual, and check that the LED blink codes match the wire colors you should have used).  Next, try the ASWC's manual programming procedure — assign the "dead" buttons to other audio functions that the ASWC didn't choose (e.g., Band, Preset Up/Down, Mute) and verify that every button works.  That will at least confirm that the ASWC is able to see all 8 of your car's buttons.

Once you've verified that the ASWC is able to see all of your car's SWCs, you can try manually programming the three phone buttons to do the corresponding phone commands.  Several people have found this works, even though the automatic programming did not assign those buttons.  For any buttons that still don't work, you can again go back and assign those to do extra audio functions.

Kenwood seen as JVC

The ASWC is detecting some recent Kenwood HUs as JVC.  The two brands are now owned by the same company and are apparently sharing some circuitry.  At one point, Metra's instructions said these Kenwood models exhibit this problem: DNX9960, DNX7160, DDX896 and DDX418.  You can solve the problem either of two ways:

  1. Use the ASWC's manual programming procedure to select "Kenwood" as the HU brand.
  1. Temporarily insert a 10k to 12k ohm resistor between the ASWC's BROWN wire and the Kenwood's SWC wire (LIGHT BLUE/YELLOW).  Metra now includes a tiny 12k resistor in the ASWC package.  This will enable the ASWC to automatically detect the HU as a Kenwood.  You can then proceed with auto- or manual programming of the SWC buttons.  After you have done that, you must remove this resistor for normal operation.
    Again, you only need to add the resistor if the ASWC auto-detects your Kenwood as a JVC.  In that case, only have the resistor connected during auto programming.

SWCs not working on Kenwood

Another customer recently alerted me to this:  Some Kenwoods have a menu option that enables/disables SWC control.  In the manual section "Setting menu items", find the option "Remote Sensor".  That actually affects both the infrared remote and SWC input (though the manual doesn't reveal this).

Additional notes

Reset button and LED holes

Remember that the ASWC's reset button is inside the hole towards the left (closer to the USB port cover).  If you need to press the button, use a blunt probe (such as a toothpick, small hex key, coffee stirrer, paper clip, stem of a Q-tip, etc.) and insert that into the hole.

The hole towards the right (closer to the ASWC's 12-pin harness connector) has the LED underneath.  Don't poke anything in there!

USB Interface

On the older ASWC (the version that does not have a micro USB port), you must NOT connect the ASWC's USB connector directly to a computer's USB port — you could fry the ASWC module.  Metra's USB-CAB interface cable converts USB to +5V TTL serial.

Their updating software will only work with certain converter cables.  If you need to update the firmware on an older module, I have the USB-CAB cables available.

The newer ASWC-1 has a micro USB socket.  You can use a regular USB cable (male micro USB to male "A") to update the firmware.

ASWC Documentation Online

The latest versions of the ASWC product manual and vehicle-specific instructions are available from their web site.  Always navigate from their home page, to be sure that you get the latest version of each document.

Be aware that Metra may post revisions to these documents "in place" (without changing the file names or URLs).  So it's not easy to tell when a file has been updated.  You can check the "document properties" in a PDF to see the "Created" and "Modified" dates (which are different than the date you saved the file to your computer).

ASWC Product Instructions

Start at their home page: www.axxessinterface.com

Click on the "ASWC-1 Vehicle Instructions" button (in column of links on the right side, below the scrolling banner pictures).

Scroll down to see "PDF Downloads:" and click the link "Download the ASWC Instructions Manual >>".

ASWC Vehicle-Specific Instructions for Subarus

From Axxess site's home page, click on the "ASWC-1 Vehicle Instructions" button (in column of links on the right side, below the scrolling banner pictures).

Select: SUBARU, (your model), (your year), and your factory radio (e.g., "WITH STANDARD AUDIO SYSTEM", "WITH NAVIGATION EQUIPPED AUDIO SYSTEM", etc.).

This brings up a link to a PDF doc for the vehicle-specific installation instructions.  Beware: Some of those PDF files may still show incorrect harness diagrams and/or pin numbers.  If theirs differ from mine, e-mail me and I'll look into it.

ASWC Firmware Release Notes

From the Axxess site's home page, in the row near the top of the page, click on "AXXESS UPDATES" to go to this page:

There you'll find a blog with release notes, as well as some press releases.  Often, Metra is a little slow to update that.  If you install Metra's WebXXpress Updater program, you can find more recent notes in a file named "ASWC Version Updates.txt", in the directory "USB Bootloader\data".

© Copyright 2010–2014 by David Carter.  All rights reserved.