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 HU's power/speaker harness, creating an adapter that is mostly "plug-and-play."
If your Subaru is a 2012-up Impreza (not WRX or STI), Crosstrek, or 2014 Forester, your factory radio harness includes a wire for the Vehicle Speed Signal (VSS). 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).
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), or one of the various SWI-* models from PAC Audio (SWI-PS, SWI-JACK, etc.— different models depending on your new HU's brand). 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 this page.
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.
Here are some options for retaining a center console USB socket with an after-market HU:
Retain Factory Aux Jack
Your factory HU has a socket on the rear for its stereo aux input. A factory harness connects from there 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:
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. Price for the aux harness as pictured is $22.
If you're planning to connect an iPod or iPhone, many recent HUs use an iPod 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.
Retain OEM Subwoofer
If your car has the rectangular-shaped OEM subwoofer under either of the front seats, similar to this:
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).
On the other hand, if you have a Forester with the odd-shaped under-seat sub shown here, that subwoofer takes a line-level (low level) signal and connects to the factory HU via additional pins on your car's aux harness. I can build my aux adapter with an additional RCA plug so you can drive your car's sub from your new HU's line-level subwoofer output, similar to this:
Price for the aux+sub adapter with 3 RCA plugs as pictured is $39, and includes a remote turn-on wire for the sub.
Additional Signals on Aux Harness
In Foresters with the OEM HU model CP635U1, and 2012-up Impreza (not WRX or STI) and Crosstrek, the factory 16-pin aux harness includes leads for the Parking Brake and Reverse Gear signals. I can add corresponding wires to my aux harness for an additional $1.50 each.
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 electronics tinkering, you should plan to use the mic that comes with your new HU.
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. I don't carry any, but have listed options and more information here.
Parking Brake Bypass
If the HU you're installing is one of the recent Pioneer AVIC X or Z models (e.g., AVIC-X940BT) and you were planning to do the parking brake bypass hack (so functions aren't locked out while driving), I have an extra wire with the proper pin that you can snap into the vacant slot on the AVIC's RCA harness. That will save you from needing to extract and transplant the Pioneer's mute pin/wire (which some people find difficult to do).
My bypass wire only fits certain AVIC navigation models, NOT any others (such as those starting with AVH-...). Tell me which model you'll be installing so I can confirm compatibility. Price is $2.00.
On most Kenwoods, you can simply connect the HU's parking brake lead to chassis ground. For other models, search on eBay or Amazon. Be sure that you find a device that is advertised to work with your specific HU model. The smaller, solid-state "micro bypass" type devices are much better than a huge 30 Amp automotive relay.
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). Cars with these OEM HU models have the OEM Motorola adapter: CZ624U1, CZ641U6, CZ601U1, CM621UB, CM601U1, CM631UD, CP625U1, CP635U1, CP403L1, CP604U1, CP603U1.
The OEM HUs in a few models (mainly some Foresters, and models with Subaru OEM navigation) have Subaru's proprietary connector. I have antenna adapters available for $8. Tell me your OEM HU's model number (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, please send the information requested on that page (in the section "To place an order").