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Crux SOOFD-27 Wiring Interface

Connect a new car stereo and retain your factory amp, subwoofer, and auxiliary input in select 2005-12 Ford, Lincoln, and Mercury models

Item #: 249SOOFD27

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Wire in a new radio

Crux's SOOFD-27 interface ensures that you can keep the factory speaker system in your Ford, Lincoln, or Mercury vehicle when you replace the factory radio. Connect the wires from this interface to the wires on the new stereo's wiring harness, and your power, ground, and factory speaker connections are covered. If your audio system has a factory amp and sub, the Crux interface can also keep them working too. The Crux interface lets you keep your car's auxiliary input active as well, but you'll have to choose a new car stereo with a rear aux input, as the Crux adapter's RCA connectors plug into that rear input.

The SOOFD-27 interface also offers the parking brake, reverse, mute, and Vehicle Speed Sensor (V.S.S.) outputs that you'll need if you're installing a navigation receiver. If you like your radio to keep playing after your vehicle is turned off, this interface also supports Retained Accessory Power (RAP) which keeps the music going until the door is opened.

Important Installation Notes

The SOOFD-27 interface is not compatible with factory SONY systems or the THX amplified systems. If you're keeping your factory sub, you'll need to choose a car stereo with a dedicated sub preamp output (full-range preamp outputs will not work). If you're keeping your vehicle's aux input, you'll want to choose a car stereo with a rear aux input, preferably RCA inputs that the SOOFD-27's RCA connectors can plug into.

Note: Most vehicles will require additional installation parts — please identify your vehicle if you haven’t done so. You can also call an Advisor for more information.

Product Highlights:

  • connect a new stereo to your factory wiring plug and retain Retained Accessory Power (RAP)
  • provides connections for parking brake, Vehicle Speed Sensor (V.S.S.), reverse gear, and illumination for installing navigation receivers
  • retains factory amp and subwoofer
  • retains your car's auxiliary input; new car stereo must have rear aux input to accept adapter's RCA connectors
  • warranty: 1 year
  • Our 60-day money-back guarantee

Crux SOOFD-27 Wiring Interface Reviews

Average Customer Review:

2 Reviews

Used to install Clarion NX404 in 2008 Ford Expedition

Written by: Cyotz from KC, MO on May 14, 2014

2008 Ford Expedition
Crutchfield Customer Review (What's this?)

I used the Crux wiring harness to install the Clarion NX404 in my 2008 Ford Expedition XLT. The truck had the base stereo with rear seat controls and front AUX input (that's it, no rear entertainment system like most have). The Crux is the only harness that said it would keep the front AUX input, which it does. The only reason I gave it 4 stars rather than 5 is that after install my rear speakers were cycling on and off. The Crux instructions didn't mention this potential problem. The issue that the Crutchfield guys helped me solve is that the rear controls were still partially active (they were supposed to be nonfunctional due to the Crux wiring harness). I had to pull the connector to the rear controls and make a jumper from the rear speaker wires running in to the rear controls and to the speaker wires running out to the speakers. Now the system works as it should have originally. If you have the rear controls and want to keep them you should probably use the PAC harness. But, if you'd rather have the front AUX than the rear controls (like me) then the Crux works. Just keep in mind that you may have to rig a bypass for the rear speakers. BTW, a big 5 STARS to the Crutchfield techs in helping me diagnose the problem. Once we got there it was easy to rig the bypass.

Pros: Keeps the front AUX input.

Cons: You lose the rear seat controls and may have to run a wiring bypass for the rear speakers for some vehicles.

Harnes adapter

Written by: Crazywelder72 from Winchester MA on August 24, 2013

2008 Ford Expedition
Crutchfield Customer Review (What's this?)

Works perfectly as designed.

Pros: Works perfectly as designed.

Cons: Can't think of any

Hands-on research

What's in the box?

Download owner's manual

  • Radio replacement interface module (for Ford/Lincoln/Mercury)
  • Wiring harness
  • Installation Instructions

Product Research


Ford/Lincoln/Mercury Radio Replacement Interface: The CRUX SOOFD-27 is a radio replacement interface for select 2006-2012 Ford/Lincoln/Mercury vehicles (w/ CAN bus systems). It facilitates the integration of an aftermarket radio to enable retention of factory features (such as RAP, Aux In, & factory sub) when replacing a factory installed radio in select Ford/Lincoln/Mercury cars (with or without amplified factory audio systems).

Compatibility: The CRUX SOOFD-27 is supported by the following 2006-2012 Ford/Lincoln/Mercury vehicles; with CAN bus system and amplified or non-amplified factory audio systems.

Make Model  Year
Ford Edge 2007-2010
Escape 2008-2012
Expedition 2007-2012
Explorer 2006-2010
Explorer Sport Trac 2007-2010
F-150/250/350/450 2008-2012
Five Hundred 2005-2007
Flex 2009-2012
Focus 2008-2011
Freestyle 2006-2007
Fusion 2006-2012
Mustang 2005-2012
Taurus 2008-2012
Lincoln MKS 2009-2011
MKX 2007-2010
MKZ 2007-2010
Navigator 2007-2012
Zephyr 2006
Mercury Mariner 2007-2010
Milan 2006-2010
Montego 2005-2010
Mountaineer 2006-2010
Sable 2008-2009
Note: Please consult Crutchfield's Outfit My Car to see if your vehicle is compatible and what additional installation accessories will be needed.

Retained Features: The CRUX SOOFD-27 radio replacement interface module retains the vehicle's factory RAP (retained accessory power) and factory amplified subwoofer. It does not retain OEM steering wheel controls.

  • Retained Accessory Power (R.A.P.): The ignition power source of many Ford/Lincoln/Mercury vehicles keeps the radio on until one of the doors is opened. This feature is called the R.A.P. (retained accessory power). The CRUX SOOFD-27 is designed to retain this feature.
  • Retains Factory-Installed Sub: The CRUX SOOFD-27 radio replacement interface module retains the factory-installed subwoofer in Ford/Lincoln/Mercury vehicles (if equipped). Your aftermarket head unit must have at least one RCA preamp output.
  • Factory Aux Input Retention: The SOOFD-27 will retain your vehicle's factory aux input. Your aftermarket head unit will need to have a rear-panel Aux input (a male mini to stereo female RCA adapter may be required, sold separately).

Navigation Outputs: The CRUX SOOFD-27 radio replacement interface module provides a VSS (vehicle speed sense), Parking Brake, and a Reverse Gear output to make installing an aftermarket Navigation radio simpler and less time consuming.

Amp Turn-On: The CRUX SOOFD-27 provides an amplifier turn-on lead for your vehicle's factory amplifiers (if equipped), and includes a built-in 5-volt regulator to provide the proper turn-on voltage.

Wiring Harness: The included wiring harness features three connectors (8-/12-/24-pin) which plug into your vehicle's factory radio harness, plus a 12-pin connector which plugs into the SOOFD-27 interface module. There are three male RCA connectors which retain your vehicle's factory Aux Input and factory amplified subwoofer. The wiring harness also provides the following bare-wire leads which will need to be hardwired to your aftermarket head unit's wiring harness.

Wire Color Function
Black Chassis Ground
Red +12 Volt Accessory
Yellow +12 Volt Constant
Orange Illumination
Blue/white Amp Turn-On
Blue Power Antenna
White Left Front Speaker +
White/black Left Front Speaker -
Gray Right Front Speaker +
Gray/black Right Front Speaker -
Green Left Rear Speaker +
Green/black Left Rear Speaker -
Purple Right Rear Speaker +
Purple/black Right Rear Speaker -
Yellow/black Park
Red/black VSS (vehicle speed sensor)
Red/white Reverse
*RED RCA Right Aux Input
*White RCA Left Aux Input
**Black RCA Factory Sub
  • *Your aftermarket head unit must be equipped with a rear-panel Aux input to retain your vehicle's factory Aux input (a male mini to stereo female RCA adapter may be required, sold separately).
  • **Your aftermarket head unit must be equipped with at least one RCA preamp output to retain your vehicle's factory amplified subwoofer.

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