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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

Find what Fits your car

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Item # 249BM57K

In stock

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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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:

Make Model Year Connector
BMW Compact (E46) 2001-2006 40-Pin Quad-Lock
3 Series E36 1999-1998 17-Pin Slide-Lock
E46 1998-2005 40-Pin Quad-Lock
E46 2006 17-Pin Slide-Lock
5 Series (E39) 1995-2000 17-Pin Slide-Lock
2001-2003 40-Pin Quad-Lock
7 Series (E38) 1990-1998 17-Pin Slide-Lock
1994-2001 40-Pin Quad-Lock
X3 2004-2006 17-Pin Slide-Lock
2006-2007 40-Pin Quad-Lock
X5 2000-2001 17-Pin Slide-Lock
2002-2006 40-Pin Quad-Lock
Z3 1996-2002 17-Pin Slide-Lock
Z4 2003-2008 40-Pin Quad-Lock
Z8 2001 17-Pin Slide-Lock
M Series 1999-2002 17-Pin Slide-Lock
Mini 2001-2005 40-Pin Slide-Lock



Amplified & Non-Amplified Systems: The CRUX SWRBM-57K works in non-amplified and analog amplified BMW audio systems. However, it is not compatible with BMW vehicles that feature a factory DSP type digital amplifier.

Steering Wheel Controls: 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.

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Customer Q&A

6 questions already asked

Is this compatible with the Kenwood DDX395?
[ Cris  May 23, 2020 ]
1 answer
This will depend largely on your vehicle. For details on installation please contact an Advisor by phone (1-800-324-9695) or online chat. They will be able to pull up your vehicle and give you the details on what you will need for an installation.
[ Calvin  Jun 15, 2020 ]  Staff
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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