Parts Needed
to install an after-market Head Unit
2011–up Impreza, WRX, STI, OBS,
Forester, Crosstrek
models without OEM navigation and
with phone / Bluetooth buttons on steering wheel

For Impreza and Forester models without phone/Bluetooth buttons on steering wheel, see this page

When you place your order, let me know you've seen my "Parts Needed" page.

Power/Speaker Wiring Harness

For all of the above models with Bluetooth (i.e., steering wheel includes Off-hook, On-hook, and Talk buttons), you'll need my 20-pin "forward" harness with 3 SWC wires ($12).  Link.

You'll need to solder or crimp my harness to your new head unit's (radio's) power/speaker harness, creating an adapter that is mostly "plug-and-play."

Vehicle Speed Signal

On these models,  the  factory 20-pin power/speaker harness includes a wire which provides the Vehicle Speed Signal (VSS) on pin #19:

  • 2012–up Crosstrek
  • 2012–up Impreza (not WRX or STI)
  • 2014–up Forester
  • 2015 WRX or STi

A few aftermarket navigation HUs can use this signal.  If your new HU needs it, I can include a corresponding wire on my harness for an additional $1 ($13 total).

Incidentally, cars with VSS on the 20-pin radio harness no longer have CAN bus there.

Steering Wheel Interface Module

The SWC wires on my harness are only part of the solution — that saves you from needing to splice into factory wires.  However, most aftermarket HUs also require a steering wheel interface module — either the Axxess ASWC (by Metra), one of the various SWI-* models from PAC Audio (SWI-PS, SWI-JACK, etc.— different models depending on your new HU's brand), or iDatalink Maestro.  More people prefer the ASWC.

Many Subaru owners have installed ASWCs and given rave reviews.  In most cases, it programs itself and is ready to go a few seconds after the first power up.  You can also manually program it if you want to reassign any buttons.  Installation is much easier than the PAC modules.

I have the ASWCs available.  See .

To install, you will need to solder (recommended) or crimp some of the ASWC's wires to my 20-pin harness and your new HU's harness.  I can't pre-wire the harnesses for you, since you will need to combine with your new HU's harness.

To connect an ASWC to a Parrot Asteroid Smart HU, you will also need the Metra AX-SWC-PARROT interface cable.  I have those available for $7.

Retain Factory USB Socket

Your factory HU has a socket on the rear for its USB input.  A factory harness connects from there to the back of the USB socket in your armrest center console.  That harness has proprietary plugs at both ends.  The harness only handles the USB socket — not aux.

Metra now makes a plug-and-play USB interface cable for Subarus, their AX-SUBUSB.  This connects between the car's plug (that is/was plugged into the back of your OEM HU) and your new HU's rear USB socket.  Picture, picture.

I have a similar adapter available for $12.  Length of the cable is ~6" (147 mm) between the two connectors.

Note: 2014–up Forester and 2015 WRX/STi switched to a Toyota-style USB connector.  I have those, also $12.

Retain Factory Aux Jack

Your factory HU has a socket on the rear for its stereo aux input.  A factory harness connects from the HU to the back of the 3.5mm aux jack in your armrest center console.  That harness only handles the aux audio connection — not USB.

If you want to retain use of your factory 3.5mm aux jack, I make an aux adapter similar to this:

Subaru 16-pin aux adapter harness with RCA plugs
(click thumbnail to see larger image)

The white 16-pin connector fits the end of the factory aux harness behind your OEM HU.  My harness retains the stereo aux jack only, not the USB.

I'm out of the RCA cables I use to make these harnesses.  I don't have an estimate on how long it will take before I have more (could be several months).  In the mean time, I can build an aux harness consisting of the 16-pin connector with three plain wires 3" long (for aux audio left, right, and ground).  To those you would need to solder a male 3.5mm plug or male left/right RCA plugs (whichever is needed for the aux input port you wish to use on the rear of your new HU).  Price $14.

Also see 'additional signals' (below) for other wires you may want to include.

Before Ordering Aux and/or USB Adapters

Study the connection diagrams in your new HU's installation manuals.  With the cables and interface adapters required for some phones or iPods, it's sometimes not practical to retain your car's factory aux or USB sockets (due to the physical layout of all the pieces).

Older iPods sometimes use an interface cable which splits out into two plugs at the rear of the HU — one to plug into a USB socket and the other into an A/V aux input (4-pole style, with both audio and video).  Your car's factory 3.5mm aux jack supports stereo audio only — it will not support video for an iPod video cable.  So if you plan to use that kind of iPod cable, you may not want my aux harness.  See this post for pictures and more information.

Also note: None of the Pioneer AppRadio models has an aux input!

Retain OEM Subwoofer

If your car has the rectangular-shaped OEM subwoofer under either of the front seats, similar to this:

Subaru OEM under-seat subwoofer
(click thumbnail to see larger image)

or either of the OEM rear subwoofers made by Kicker, those types of subs will work with an after-market HU without any modifications or special wiring needed.  All of those subs have a T-harness which taps the front speaker outputs and power from the radio's power/speaker harness.  See this post for details (post #4 in my 'Subaru stock HU Info' thread on NASIOC).

Forester "odd-shaped" Sub

If you have a Forester with the odd-shaped under-seat sub shown here, that subwoofer requires a line-level (low level) signal, supplied from the factory HU via additional pins on your car's aux harness.  I can build my aux adapter with an additional green male RCA plug so you can drive your car's sub from your new HU's line-level subwoofer output, similar to this:

Subaru 16-pin aux+sub adapter harness with RCA plugs
(click thumbnail to see larger image)

Price for the aux+sub adapter with 3 plain 3" aux wires plus the green RCA plug is $30, and includes the 8" BLUE/WHITE remote turn-on wire for the OEM sub.  This version is only needed for the odd-shaped OEM sub.

Additional Signals on Aux Harness

In these models, the factory 16-pin aux harness includes leads for the Parking Brake (pin #15) and Reverse Gear signal (pin #16):

  • Foresters with factory-installed HU models CP635U1, CP435L1, CP335R1, or CP235K1
  • 2012–up non-nav Impreza (not WRX or STI)
  • All non-nav Crosstrek

I can add corresponding wires to my aux harness for an additional $1.50 each.

Note: 2014–up Forester and 2015 WRX/STi do not have the parking brake or reverse gear signals on the 16-pin aux harness.

harman/kardon amp trigger

In 2014–up Forester and 2015–up WRX/STi with the harman/kardon amplifier and speaker system, the h/k amp remote trigger signal is pin #5 on the 16-pin aux harness.  If you are retaining the factory h/k amp, you must supply +12V to this pin for the amp to work.

I can build a harness with just that one wire for $10, or a harness with that and any of the other wires (e-mail me for pricing).

Can't Retain OEM Microphone

For the Bluetooth phone feature, your car has a factory microphone hidden behind the map light cluster.  The mic is in a small module with an amplifier circuit (see this thread).  The module's audio output is not like an aftermarket HU's mic.  Nobody has documented a good way to interface the OEM mic to an aftermarket HU.  See this thread for one attempt.  Unless you're especially skilled at analog electronic circuit design, you should plan to use the mic that comes with your new HU.

Retain OEM Camera

If your car has a factory-fitted rear view camera that is displayed on your OEM HU, I can probably provide a harness to retain the camera with an aftermarket HU.

Note: Subaru HUs supply 6 Volt power to the OEM cameras.  The cameras operate internally at 3.3V and have a built-in voltage converter.  In most models, you should give the camera something close to 6V, to prevent the camera's converter from overheating.  However, the voltage converter in the Crosstrek's camera has been confirmed to work with an input up to 40V without any problem.

E-mail me to discuss what kind of "OEM rear camera retention" harness you'll need.

Note that the 8- and 16-pin camera harnesses currently listed in my 'Products' pages are to connect an aftermarket camera into certain OEM HUs.

If your car has an OEM camera being displayed in the mirror, I don't have any plans to offer a harness to re-direct that to an aftermarket HU.

Multi-Function Display (MFD)

Recent models with the new dash design have a Multi-Function Display (MFD) at the top of the dash, above the head unit and A/C vents.

On some models, the MFD displays information from the HU (audio source, radio station, artist, song title, etc.).  When you switch to an aftermarket HU, you will loose that feature, since it requires a proprietary data interface (which no aftermarket HU has or is likely to have).  However, all other (non-radio) data screens on the MFD will continue working as before.

When you install your new HU, you must disconnect power from the MFD for more than 30 seconds, to make the MFD "forget" it had ever seen your factory HU (otherwise the MFD will complain that the OEM HU is missing).  You can do this by either disconnecting the negative terminal from your car's battery, temporarily removing the fuse for the circuit which powers the MFD, or unplugging the MFD's power harness (12-pin).

Some models have an OEM camera shown on the MFD.  I've made harnesses for a few people to re-direct the OEM camera to an aftermarket HU.  I've also made harnesses to connect an aftermarket camera to an MFD in cars which don't have a factory camera.  I can also make a harness to re-direct an OEM camera from the MFD to an OEM HU with rear camera capability.  However, I have suspended offering all of these MFD camera harnesses, pending some additional research on the MFD.  If you would like to be notified when these are available again, let me know.

Dash Kit

The factory HUs in all 2008–up Impreza/WRX/STI, 2009–up Forester, and Crosstreks have a face that is non-standard size (8" wide instead of the standard DIN 7").  You'll need a dash kit to fill the gap or which has a smaller DIN-sized opening.

Models with the new dash design (2012–up Impreza & Crosstrek, 2014–up Forester, 2015–up WRX/STi) require different dash kits than the previous 2008–up models.

I don't carry any dash kits, but have listed options and more information here.

AVIC Parking Brake Bypass

See this page: Pioneer AVIC parking brake bypass wire.

My AVIC bypass wire does not fit any of the new AVIC NEX models, nor any of the old models (AVICD3, Z2, FxxxBT, UxxxBT, etc.).  For all of these other AVIC models, see the forums at  A software-only hack was found for the NEX navigation models (and it's been confirmed that you don't even need to connect the HU's parking brake lead).

On most Kenwoods, some recent JVCs, Parrot Asteroid Smart, most Chinese HUs, and perhaps all HUs designated for markets outside North America, you can simply connect the HU's parking brake lead to chassis ground.

I do not have parking brake bypass devices for any other aftermarket HU models (including Pioneer models starting with AVH–...).  Search on eBay or Amazon.  Be sure that you choose a device that is advertised to work with your specific HU model.  The smaller, solid-state type devices are much better than a huge 30 Amp automotive relay.

Antenna Adapter

Most recent Subaru HUs have a standard Motorola antenna socket on the back, and the car already has an OEM antenna adapter (to convert from Subaru's proprietary antenna plug to Motorola).  I think all non-nav Impreza, Crosstrek, and Forester HUs with built-in BT and USB have the Motorola socket.

Cars with these OEM HU models definitely have the OEM Motorola adapter (so they do not need an aftermarket antenna adapter):

CF225KM, CF425LM, CF435LH, CF525SM, CF605UL, CF625UM, CF646UH, CF735CH, CM221KB, CM421LB, CM621UB, CM631UD, CP235K1, CP325R1, CP335R1, CP425L1, CP435L1, CP625U1, CP635U1, CV629UM, CZ201K1, CZ224K1, CZ324R1, CZ341R6, CZ401L1, CZ441L6, CZ601U1, CZ605UL, CZ624U1

The OEM HUs in a few older Forester models, and cars with Subaru OEM Kenwood navigation have Subaru's proprietary connector.  I have antenna adapters available for $8.  If you're not sure, and your model is not listed above, tell me your OEM HU's model number (usually printed on the front) and I can confirm whether you'll need one.

To Place Your Order

See this page for shipping and payment options.  Let me know if you have any questions.  When you're ready to place your order (or for an itemized quote with shipping), please send the information requested on that page, in the section "To place an order".

Remember to mention you've seen this "Parts Needed" page.