Contact us
Close contact box

PAC RP4.2-BM21 Wiring Interface

Connect a new car stereo and retain steering wheel controls and warning chimes in select 2006-2015 BMW vehicles

Item # 541RP4BM21

Installing a new car stereo can often mean losing your vehicle's steering wheel audio controls and other factory...

Find what Fits your car

Installing a new car stereo can often mean losing your vehicle's steering wheel audio controls and other factory...

California customers:
Please click here for your Proposition 65 warning.

Need help?
Contact our Virginia-based experts.

Item # 541RP4BM21

Ships free

In stock
$129.99

About the PAC RP4.2-BM21 Wiring Interface

Upgrade the radio in your BMW

Installing a new car stereo can often mean losing your vehicle's steering wheel audio controls and other factory features. PAC's RP4.2-BM21 wiring interface solves this problem, allowing you to install a new receiver in your BMW while retaining your steering wheel controls, warning chimes, and (non-fiber-optic) factory amplifier. The interface also supplies the connections you need to install a navigation receiver. Warranty: 1 year.

Upgrade the radio in your BMW

Installing a new car stereo can often mean losing your vehicle's steering wheel audio controls and other factory features. PAC's RP4.2-BM21 wiring interface solves this problem, allowing you to install a new receiver in your BMW while retaining your steering wheel controls, warning chimes, and (non-fiber-optic) factory amplifier. The interface also supplies the connections you need to install a navigation receiver. Warranty: 1 year.

Important Note: this wiring interface works with car stereos made by Alpine, JVC, Kenwood, Clarion, Pioneer, Sony, Fusion, Advent, Boyo, Dual, Lightning Audio, Rockford Fosgate, and Visteon.

READ LESS

What's in the box:

  • Radio replacement/SWC interface module (for BMW)
  • Vehicle/interface harness
  • 16' Constant power wire (in-line 10A fuse)
  • External speaker (attached 8' harness)
  • 4' Factory chime harness
  • 2 Screws
  • 2 Wing-nuts
  • Two-sided tape
  • Instructions
MFR #RP4.2-BM21

Customer reviews

Loading reviews...

PAC RP4.2-BM21 Wiring Interface reviews

Average review:

12 reviews

Thanks for submitting your review

Filter by rating

Customer photos

Sort reviews

Sort by:
Items per page:
View page:

Verified customer (What's this?)
Verified employee purchase (What's this?)

Pros:

Cons:

Crutchfield response

<< >>

More details on the PAC RP4.2-BM21 Wiring Interface

Stacey B.

Product Research

Features

Radio Replacement Interface (for BMW): The PAC RP4.2-BM21 interface allows the replacement of a factory radio in select BMW vehicles. Using this interface will retain factory features such as: steering wheel controls (SWC), iDrive controls and warning chimes (including rear park assist and front collision detection). The RP4.2-BM21 also provides data bus driven outputs such as data driven accessory power, vehicle speed signal (VSS), illumination, reverse, and parking brake.

Vehicle Compatibility: The RadioPRO 4 RP4.2-BM21 is compatible with the following BMW vehicles (as of 4/5/2016):

Make Model Year
BMW 1 Series 2011-2014
3 Series/M3 2006-2015
5 Series/M5 2010-2014
6 Series 2011-2014
Notes:
  • Incompatible with vehicles equipped with the upper display screen above radio (CCC or CIC systems). This screen is not retained if the factory radio is removed, and you will lose the ability to adjust some vehicle settings. Radio replacement is not recommended for those applications.
  • Does not retain factory amplifiers equipped with Fiber-optic input.
  • BMW 1 Series vehicles equipped with navigation are not compatible.
  • 2006 BMW 3 Series coupe is not compatible.
Radio Select Switch: The radio select rotary switch on the side of the interface must be adjusted to the proper radio setting before plugging the interface into the vehicle. The RP4.2-BM21 is compatible with Alpine, JVC, Kenwood, Clarion, Pioneer, Sony, Fusion, Advent, Boyo, Dual, Lightning Audio, Jensen, Rockford Fosgate, and Visteon aftermarket radios (see owner's manual for appropriate dip-switch setting).

+12V Outputs: The PAC RP4.2-BM21 integrates with your BMW's 12-volt electrical system.

  • Hardwired +12V Constant Lead: BMW's power management system causes the constant power wire behind the radio to drop out after the key has been removed for 30 minutes. It may be necessary to run a new 12v constant wire (included) from the battery (located in the trunk) to the aftermarket radio.
  • +12V/10A Accessory Output: In many BMW vehicles, there is no 12-volt accessory wire in the factory harness, which requires the installer to run an accessory wire to the fuse box or underneath the steering column when installing an aftermarket radio. PAC's RP4.2-BM21 is designed to provide a data controlled 12V/10A switched accessory output (red wire).
  • Retained Accessory Power (R.A.P.): The ignition power source of many BMW vehicles keeps the radio on until one of the doors is opened. This feature is called the R.A.P. (retained accessory power). The RP4.2-BM21 will retain this feature.
  • Programmable +12V Output: The Red/White wire on the interface can be programmed via the RadioPRO app to provide a pulsed or latched 12v output which can then be assigned to any of the vehicle's factory SWC buttons. When assigned, the factory SWC button will activate the pulsed or latched output to control external accessories

Factory Amplifier: The PAC RadioPRO RP4.2-BM21 will retain your BMW's factory amplifier. However, this interface does not retain factory amplifiers equipped with a Fiber-optic input. The interface features RCA connectors that plug into your aftermarket radio's front & rear channel pre-outs.

Programmable SWC: The interface comes pre-programmed for all of the vehicle's factory SWC functions and does not require programming, unless you wish to re-assign the SWC functions to different buttons or create secondary functions. Use of this interface also allows you to program two radio functions to each SWC button by using short press long press dual command functionality. The SWC functions can be easily programmed; see default SWC button assignments in the included user manual. The interface retains programming even if your vehicle's battery is disconnected.

Note: The SWC harness contains a Blue/Yellow wire and a 3.5mm connector. You will only use one of the connectors, based on your type of aftermarket radio. The Blue/Yellow wire supports Kenwood and newer JVC receivers. The 3.5mm jack supports Alpine, Jensen, Older JVC, Clarion, Pioneer, Sony, and Dual radios. Not compatible with Soundstream head units.

iDrive Control: The PAC RP4.2-BM21 interface can retain your BMW's i-Drive control system and even operates some features of your new aftermarket radio (tuning, etc.).

Warning Chimes: The PAC RP4.2-BM21 retains warning chimes (including rear park assist and front collision detection). The factory warning chimes are audible either through the factory door speaker or through a separate speaker in the upper dash. In the event disconnecting the radio results in the vehicle loosing the chimes, there are two ways to retain them. The RP4.2-BM21 must either be connected to the vehicle's hands-free speaker in the driver side under dash, (using the supplied harness) or connected to the supplied speaker. The speaker can then be routed and mounted where desired. In addition, the RP4.2-BM21 removes the SOS error light from cluster after factory radio is removed.

Navigation Outputs: The PAC radio replacement interface provides wired outputs for navigation radio installation; including a VSS (vehicle speed sense), Parking Brake, and a Reverse Gear output to make installing an aftermarket navigation head unit simpler and less time consuming.

Wiring Connection Chart: The included wiring harnesses features the following hardwire connections.

Wire Color Function
Red +12 Volt Accessory
Yellow +12 Volt Constant
Black Ground
Blue/White Amp Turn On
Orange/White Illumination/Dimmer
Light Green Parking Brake Detection (-)
Pink VSS Output
Purple/White Reverse Output (+)
Red/White +12V Programmable Output

RadioPRO App: PAC offers a Windows compatible RadioPRO App software program to help you configure the interface. Use of the RadioPRO App allows you to do the following.

  • Red/White wire output behavior
  • Aftermarket radio Parking Brake Sequencing
  • Adjust warning chime volume level
  • Update Product Firmware
  • Read Firmware/Hardware Versions
  • Access Product User Manuals
Note: The interface must be connected to the vehicle and your Windows laptop when using the RadioPRO App.

Loading accessories...

Customer Q&A

Q
Crutchfield asked: Why did you buy this?
A
part of the Crutchfield prescribed bundle with my head unit purchase [ Paul  Feb 28, 2019 ]
A
Upgrading factory receiver [ marvin  Aug 16, 2017 ]
A
It's supposed to be a all in one kit [ tom  Feb 03, 2017 ]
A
part of installation package [ Vincent  May 10, 2016 ]

1 question already asked

Q
Hello, how are you doing? I am contacting you because I own a 2006 BMW 330I and installed a Kenwood DDX9902s. I decided to purchase the different additional parts in order to install it. My problem right now is that my brake lights stay on. They do not go out, they are constantly on which presents a great danger to drivers behind me and myself. Can you please provide me with some guidance? Thanks.
[ kenneth  May 18, 2016 ]
1 answer
A
With your purchase from Crutchfield, feel free to contact our Tech Support team. They can walk you through the connections on the product and see if there may be a fix. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website.
[ Kenny  May 18, 2016 ]  Staff

Loading articles...

TOP