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Crux SWRBM-57K Wiring Interface

Connect a new car stereo and retain the steering wheel audio controls in select 1991-2006 BMW vehicles

Item # 249BM57K

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Item # 249BM57K

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About the Crux SWRBM-57K Wiring Interface

You'll only be able to retain your steering wheel audio controls with a compatible car stereo made by Alpine, Blaupunkt, Clarion, Jensen, JVC, Kenwood, Pioneer, or Sony. No other brands are currently compatible.

Keep your steering wheel controls

Crux's SWRBM-57K interface ensures that you can keep the factory steering wheel controls in select 1991-2006 BMW models when installing an aftermarket radio. Connect this interface to the wires on your new stereo's wiring harness, and you've covered the power, ground, and factory speaker connections for your new stereo. The interface works with BMW models with the I/K-Line bus, and includes 17-pin and 40-pin connecting harnesses.

Product highlights:

  • connect a new stereo in select 1991-2006 BMW models
  • retain your steering wheel controls with select car stereos
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # SWRBM-57K

What's in the box:

  • Radio replacement interface module (for BMW)
  • 17-Pin harness
  • 40-Pin harness
  • Steering wheel control harness
  • Instructions

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Crutchfield response

<< >>

More details on the Crux SWRBM-57K Wiring Interface

Stacey B.

Product Research


Radio Replacement Interface: The CRUX SWRBM-57K is a radio replacement interface for select BMW vehicles. It facilitates the integration of an aftermarket radio to enable retention of certain factory features when replacing a factory-installed radio and is pre-programmed for retention of steering wheel controls.

Vehicle Compatibility: The CRUX SWRBM-57K radio replacement interface works with the following 1990-2008 BMW vehicles using I/K-Line Bus (factory non-amplified systems only):

Make Model Radio Year Harness
Mini Cooper Business 2001-2005 40-Pin
BMW Compact (E46)
Navigation 2001-2006 40-Pin
3 Series (E36) Business 1990-1998 17-Pin
(E46) Business 1998-2006 17-Pin
Navigation 1998-2005 40-Pin
5 Series (E39) Business 1995-2000 17-Pin
Business 2001-2003 40-Pin
7 Series (E38) Business 1990-1998 17-Pin
Navigation 1994-2001 40-Pin
M Series Business 1999-2002 17-Pin
X3 Business 2004-2006 17-Pin
Business 2004-2007 40-Pin
X5 4:3 Navigation 2000-2001 17-Pin
Business 2002-2006 40-Pin
Z3 Business 1996-2002 17-Pin
Z4 Business 2003-2008 40-Pin
Business Navigation
Z8 Business 2001-2002 17-Pin

Steering Wheel Control Retention: The CRUX SWRBM-57K features a steering wheel control output for Pioneer, Sony, Alpine, Clarion, Kenwood, JVC, and Blaupunkt aftermarket head units. The included steering wheel cotnrol harness provides a 3.5mm connector or light blue/yellow wire for your aftermarket radio. Only one type of connector will be used based on your type of aftermarket radio. There are also dip switches on the interface module that will need to be set for your type of aftermarket radio.

Note: Please see the included instructions for which SWC harness and which dip settings to use for your brand of aftermarket head unit and type of vehicle.

Wiring Harness: The CRUX SWRBM-57K includes two wiring harnesses; a 17-pin harness and a 40-pin harness (only one harness will be used based on your BMW's model and year). Either harness will plug into the SWRBM-57L interface module and your vehicle's factory radio harness, plus contain the following bare-wire leads which will need to 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 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 -

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Customer Q&A

Crutchfield asked: Why did you buy this?
this was a necessary purchase to do as "Professional" installation as possible to accommodate a tight space in a European "Roadster" with a U.S. "Head" Unit...I am looking forward to my sister enjoying some modern day features in her "Old Ride"........ [ Arlette  Jan 13, 2020 ]
After extensive consultation with Nemo one of your advisers (really knowledgeable person) . [ jose  Sep 09, 2019 ]
I purchased this item so I could complete a professional proper installation and utilize the steering wheel controls. [ JAMES  Feb 14, 2019 ]
In order to keep my steering wheel controls [ Daniel  Oct 19, 2018 ]
Everthing mates to my radio unit to the old wires with this interface. [ Michael  Oct 04, 2018 ]
necessary for installation [ Timothy  Jun 11, 2018 ]
I'd rather not decipher the wiring myself. [ Boyd  May 30, 2018 ]
included in installation package [ James  May 20, 2018 ]
My advisor recommended it for my product. [ Dylan  Jan 29, 2018 ]
I always wanted my controls from there [ Mickey  Nov 23, 2017 ]
Where do I put all these wires? I'm sure this will make it easy to install. [ Jon  Nov 15, 2017 ]
Tech support specifically recommended it for an easy installation. [ Albert  Oct 28, 2017 ]
Want to make sure everthing works as close to OEM as possible. [ ABLE466  Oct 17, 2017 ]
I trust crutchfield experts to assemble all the correct accessories and feel confident that everything will work and fit as it should. [ Tracy  Aug 22, 2017 ]

5 questions already asked

Will this work with a 2008 z4 with Top HiFi system with DSP Carver amplifier?
[ Cornell  Aug 10, 2019 ]
1 answer
This Crux wiring interface will work in the 2008 BMW Z4 models that came without factory installed navigation to help install a new radio, but does not keep the stock amp working with the new radio. Speaker wire will need to be installed bypassing the stock amp.
[ Paul  Aug 19, 2019 ]  Staff
What swc functions are actually retained for on my 2005 mini cooper r50 hardtop base without h/k or navigation system with the kenwood Execlon radio? Will I be able to reprogram any of the buttons? And I have 6 buttons now 4 of which are functional due to lack of built in bluetooth will I be able to use all six buttons with this head unit...?
[ Whitestallion  Jun 18, 2019 ]
2 answers
Mine all work just as before. Good luck..
[ Dennis L  Jul 18, 2019 ]
You will want to contact an Advisor by phone (1-800-324-9695) or online chat to discuss compatibility with your factory system. They will be able to pull up your vehicle and see if this will integrate. If it does not, then they will also be able to discuss other options with you.
[ Krissy  Jun 24, 2019 ]  Staff
Is this intended to work with the factory amps?
[ Ed  Aug 20, 2018 ]
1 answer
Yes it should. I used this harness to put a kenwood reciever into my bmw 328i with the Harmon Karden sounds system and it worked like a charm. Boosted the sound quality drastically, and bumps as if I have a subwoofer when I don't.
[ Sean  Aug 20, 2018 ]
is this compatible with the jvc kd-r988bts? if so how do i install it
[ Evan  Feb 20, 2018 ]
1 answer
This CRUX interface is compatible with that JVC receiver. It has bare wires that you will match to the bare wires at the end of the JVC harness. You will get a color code chart for this interface so you can use the chart that came with the JVC so you can make sure the wires are properly matched (function for function). Also, instructions are sent with it on how to program the steering wheel radio control interface to a JVC receiver. And we have technical support that can help with any part of this connecting of wires and programming of the steering wheel radio control interface. My Bio:
[ Paul  Feb 26, 2018 ]  Staff

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