Bluetooth connectivity has become so customary on vehicles from the past five years or so that it’s quite a shock to drive an older car and realize that you actually have to pick up your phone and hold it to your head while driving.  What’s more of a concern is the ever more restrictive laws requiring the use of a hands-free device, it’s already been a requirement on Federal installations for some time.  Bluetooth ear buds don’t cut it either, the MPs don’t approve and they are just a hassle and you end up looking a bit of a fool.  Fortunately several companies offer aftermarket solutions that integrate with the factory stereo, an absolute requirement for me.  I refuse to install a flashy aftermarket stereo in the M Coupe, if only a stock-looking option were available.  So after some research, I settled on the GROM USB Bluetooth Android iPod adapter, which offers the ability to connect an iPod, USB drive, and stream Bluetooth audio in addition to the hands-free calling.


This is the complete GROM USB setup. The cables exiting the left of the black-box plug directly into the pre-existing OE CD-changer wiring found near the factory amplifier. The three PS2 cables connected to the left include a iPod cable (with charging), a USB cable, and the Bluetooth dongle and microphone.

The GROM simply plugs into the stock CD-changer connectors.  My Coupe did not come with a CD-changer, I just simply removed the blank plate and you can find the two irregular shaped plugs.  GROM also includes a noise filter & inline fuse box for the power lead.  I mounted the box with industrial Velcro on the inside of my crossover mount, beside the JL amplifier.

GROM black box mounted

The GROM black box mounted to the inside of the crossover mount, to the left of the amplifier in this photo. Note the USB/iPod/BT cable routed over to the center console.

So where to mount the included microphone?  The kit includes a small microphone clip and 3M double-sided tape to mount it on any interior surface, but that just screams aftermarket to me.  A little digging on the interwebs revealed that BMW offered a factory mobile phone option (parts list at bottom), which included a microphone mount located where the sunroof button resides.  Ron Stygar pioneered this back in 2002, but I haven’t seen many others go this route.  It’s simple and elegant solution, requiring only a few inexpensive parts, you just have to have the guts to slice into a virgin headliner.  I’ll let the pictures do the talking.

Creating a template for the microphone mount

Creating a card-stock template for the microphone mount, showing where to cut the headliner.

Template taped into place

Template taped into place with first cuts already made. I positioned it based on the screw mounting hole which is already present and can be seen after removing the OE sunroof button.

Microphone clip glued in place.

I took the GROM microphone mount and sanded off the small ball mount. I tried several plastic adhesives but found that 3M urethane bumper epoxy worked the best (allowing a small amount of flex.)

Wires run up A-pillar

The microphone wires were run up the A-pillar, after wrapping it in a protective loom. The excess was tucked under the headliner, covered in foam tape to keep the rattles at bay.

Microphone install completed

The final product. Completely stock looking, because it is OEM. An added benefit is that the larger microphone mount secures the headliner and interior lights more rigidly than before.

USB and iPod cables run through center console

Here are the USB and iPod cables run through the bottom of the center console storage bin. There is a preexisting removable “door” that allows for easy routing. I notched this plastic piece to allow for re-installation.

Cubby reinstalled.

The center console reinstalled showing the routing of the wires. The store neatly underneath the Leather-Z arm rest when not in use, with enough slack to access an iPod while driving.

Bluetooth dongle location.

You can see the small black rectangular Bluetooth dongle antenna secured in place just to the left of the shifter.

Parts list:


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