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Phone Charging & Signal Boosting

  • Model & Year: 95-01 7-Series, U.S.
  • Expertise: Beginner
  • Date: August 16, 2019
  • Updated: July 21, 2020
  • Time Estimate: 2 hours

Tools Required

  • Basic hand tools

Facilities Needed

  • None

Parts Required

  • Eject Box, 84-21-2-222-122, $105 list,
  • Snap-In Adapter (phone specific or universal), details below,
  • Wiring Adapter, 84-10-9-205-271, $25 list,
  • Antenna Adapter, 84-32-0-027-140, $14 list, more below.

NOTE: The eject box has been discontinued. Search the web using keywords "BMW 84212222122" to locate vendors. The antenna adapter has also been discontinued. See "Adapters" below for alternate connection.

The eject box fits E38, E39, E46, E53 X5, E83 X3, and E85 Z4, and comes with a removable storage tray, which provides a finished look and extra utility value when snap-in adapters are not in use.

Getting Started

Have you ever wanted your cell phone to look like it belongs in your car instead of being an afterthought? Are you tired of your phone sliding around unsecured while plugged into unsightly charging cables lying haphazardly on the center console? Is your USB power supply finicky? What if your phone's power and signal requirements could be integrated into a factory solution? Well, it's possible!

Eject box installed
Eject box with iPhone SE snap-in adapter

Since the late 1990's, BMW's with factory phones (or those pre-wired for phone) have two connectors located under the center armrest providing: 1) a power supply and 2) a cable routed to the roof antenna. Furthermore, cars with factory phones even have a cellular booster (antenna amplifier).

It's time to make use of this little-known capability built into our cars! But how to do that with personal cell phones instead of useless factory phones?

BMW sells a generic "eject box" (phone interface) that installs into the center armrest in place of the utility tray (or existing factory phone) which connects to the power supply and antenna cable. Phone-specific "snap-in adapters" (phone cradles) then mate with the eject box, charging the phone while transmitting its network signal thru the roof antenna. This assures the best possible cellular reception while discretely supplying power to your phone without exposed wires...all while secured in a handsome, factory-made part!

And it's almost plug-n-play: the wiring adapter needs a few pins swapped and, the antenna connector needs to be updated (details below).

An eject box is the most sophisticated way to integrate a phone into your car. Now, streaming audio from your phone is much more practical since phone power is always at hand. And if streaming from a data source such as Pandora or Spotify, your music will flow with reduced interruptions from signal loss. Placing or receiving calls will be accomplished with optimum signal levels regardless of geographic location.

NOTE: Since the E38 7-series was designed before the age of cell phones, some phones may be too wide to fit the armrest. Limiting width is about 2.65 inches. So for example, iPhones thru version 8 should fit, but the 8 Plus will not. Verify your phone fits by placing it between the two armrest pads. If the pads can be raised without interfering with the phone, it fits.

Phone charging & signal boosting works independently of your installed electronics. Of course, your phone needs to remain connected to its snap-in adapter in order to benefit. Therefore use speakerphone when calling or, for optimal convenience, use a factory Bluetooth TCU. Streaming audio thru an aftermarket device such as a Grom (or factory "New Gen" nav radio) will work as before. And boosted cellular reception will increase the utility value of Avin aftermarket navs, which require a continuous data connection.

Phones and Snap-Ins

BMW accommodates a wide variety of cellular phones including Blackberry, Apple, Motorola, Siemens, Samsung and more, going back over a decade.

Until recently, BMW required unique snap-in adapters for each make and model of phone. This required purchasing new snap-ins when changing or upgrading phones. As another limiting factor, these snap-ins wouldn't accomodate the extra size of phones protected in cases. Thankfully, BMW introduced universal snap-ins in 2014 for both Andriod and Apple, featuring inductive coupling of the external antenna:

Universal snap-ins accommodate all current phones, the only limiting factor being phone width.

Earlier phones such as iPhones thru version 4 and Samsungs thru S4 still require unique snap-ins however, and iPhones thru version 7/8 have dedicated snap-ins available. So for example, iPhone 8 owners could use either the dedicated snap-in or universal. And while universals accommodate phones in cases, they also require manually connecting your phone to the tether cable (versus the wire-free look of dedicated snap-ins). On the other hand, the universal's tether cable allows the phone to be removed for better viewing while maintaining power.

Too Cool! In 2016, BMW introduced a wireless eject box:

Secure your phone between the two retainers to obtain inductive coupling of both charge and antenna. Made for current BMW's, it will not fit E38 7-series without modification. No seperate eject box or snap-in required. Made for phones that support wireless charging (ex: iPhone 8-on, Galaxy S8-on, etc.).

To locate dedicated snap-in part numbers for older phones, navigate to RealOEM.com and select a current BMW model (such as the current 7-series). Then select the Retrofitting/Conversion parts group and scroll down to the Communication and Information section. (Such parts are not listed under the E38 7-series since they did not exist when the E38 was made.)


Wiring adapter '271 is still available from BMW to join the 18-pin female power plugs found on the eject box and under the armrest. But antenna adapter '140 was discontinued in late 2010 (image A below). Not to worry. There is an easy alternate solution.

Since the car's threaded antenna connector is no longer of much value, it may be snipped and replaced with a FAKRA connector (as found on adapter '140) to mate directly with the eject box. Install a universal Z type connection (color: aqua) so that it will fit as many devices as possible. This will both update the antenna cable and make it more user-friendly. If you prefer the "proper" color-matched connector, purchase a D type instead (color: violet).

As shown in image B above, a FAKRA male crimp connector for RG58 cable can be found thru online vendors such as eBay and Amazon (about $6). It's important the connector is sized for RG58 cable (used for the antenna) which has a 5mm diameter as opposed to the 2.5mm diameter found on smaller RG174 cable (used for the eject box). The two different cable sizes will be of no consequence when joined using the FAKRA connetion.

TIP: Search YouTube for helpful illustrations in making this new connection. While the following video is not specifically for FAKRA connectors, it's very helpful: SMB Male Crimp Connection.

Note the car's existing antenna connector seems to be a proprietary size. (Don't be fooled: it's not an F-type thread as found on RG6 coax cable. Nor is it a TNC, FME, or SMA size. Ask me how I know.)


The eject box can be installed in about 30 minutes without removing the armrest. Wiring modifications will take about an hour. Heat-shrink tubing is recommended instead of electrical tape when wrapping contacts.

Eject Box Installation

1) Slide armrest fully forward, then pry up and remove rear cover (image A below). Locate both the black 18-pin connector and antenna connector (image B below).

2) Gently pry up the storage trays located under each pad (image A below). Then, release the clips holding the center storage tray (image B below). Remove center tray.

NOTE: It's likely the plastic storage trays have deteriorated with age. Additionally, upon removal, they will probably suffer broken attachment points. This hampers reassembly and may require replacements (part numbers 51-16-8-215-743/4).

3) Insert eject box cables thru opening in center floor of armrest and thread cable bundle rearward, out the back. See image below. Then, secure eject box in center slot and re-install the two storage trays.


4) Re-pin wiring adapter to match your car's 18-pin connector.

NOTE: Since this adapter was made for E85 Z4, re-pinning is needed. The wiring example below is for E38's built from 9/00. Others may be slighly different. Only power and ground pins are required. Use a voltmeter to confirm these pins on your car's connector, then pin accordingly.

Gently release the catch lever on one end of the adapter and slide off cover to reveal gang connector (image A below).

Re-pin adapter as shown in table below. To release pins, use a small screwdriver or similar tool to press down on its retainer tab while gently pulling the wire (image B above). Pin numbers are stamped on the connector.

Pin Pin Color Type
2 17 brown/black ground
5 8 red/blue power
13 - brown/white cradle on
14 - blue/white unknown
E38's from 9/00

Pin 13 should be removed and will be grounded seperately (in next step). Crimp a generic terminal onto its pin for this purpose. Pin 14 should be removed also and then wrapped. Remaining pins 1 (black: ULF pairing) and 16 (green: data bus) can be ignored. Final configuration should resemble image C above.

5) Prepare ground location for adapter pin 13.

The armrest's metal frame has two open screw positions ideal for use as a ground location. Use a metric machine screw with washer, as shown in step 6 image below.

6) For cars with TCU's (thru 8/00 and from 9/00 without SES): Car connector pins 11 and 14 need to remain jumpered in order to hear phone audio. Slide off connector cover (as in step 4 image A), remove pins 11 and 14, then jumper them together seperately, outside the connector, as shown in image below.

7) Prepare the car's antenna cable for the eject box by snipping off threaded connector and crimping on a male FAKRA connector (as discussed in Getting Started above). After stripping cable end, solder new FAKRA tip onto exposed antenna wire, then crimp the connector in place. Although a crimp tool is ideal, common pliers or vice grips will suffice for crimping the metal sleeve.

8) Connect adapter wiring to eject box for both power and antenna, then attach connectors to car. Be sure to attach re-pinned adapter end to car connector.

9) Secure adapter pin 13 ground to armrest frame, then tuck wiring adapter underneath frame along with antenna adapter, leaving as much room as possible for eject box cabling to move in rear area of center console. See image below (note red terminal used for pin 13 ground).

10) Install snap-in adapter of choice, then test your installation by turning ignition switch to position 1 (accessory). You should have power at the phone. When in-call (with or without Bluetooth TCU), you may see additional signal strength bars displayed on your phone or nav/MID (or gain a signal where previously there was none).

Congratulations! You're now the envy of your friends when they ask "what is that?".

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Willis, TX, USA