Phone will not connect after trying all suggestions

Car: 2003 Volvo S60 T5
Head Unit: HU-803 (VOLVO Brand)
Grom Unit: USB3 with Bluetooth dongle and microphone
Phone: Samsung Galaxy S7 Edge
Purchased: 6/13/2017

I was trying to connect my phone to the unit/dongle and it would not connect nor find the unit. The first time I had used it, it connected and worked.

So essentially I had tried all of the tips and tricks and nothing seems to get the Bluetooth to work. Using USB works so I know that something is working somewhere.

It's just the fact that the Bluetooth was not found by any of the three phones I had to test with.

Used the Scan button suggestion but there was no sound nor any reset apparent.

Big reason to get this addressed is I have a 3000 mile trip coming up soon.


  • Hello,
    The best way to address this issue urgently is via tech support ticket at

    The other suggestions are:
    1. Make sure that GROM-BTD is still plugged-in into the USB3 box. Check all connections. It can go to either EXT1 or EXT2 port on USB3.
    2. Try to reset the Bluetooth until you hear the "beep" sound. Here are the reset instructions:

    • 1. Start GROM mode changing process: press FM-->CD You will hear the current mode announce
    • 2. Press "Scan" button twice within 30 seconds
    • 3. You will hear low tone beep sound, that means that the Bluetooth connection has been reset.
    • 3. If that does not help - try to disconnect and reconnect the main USB3 module from the vehicle cable that goes to your stereo. After that perform Bluetooth reset, restart your phone and try to connect.

    Note that you have 3 minutes to connect and pair your phone when you start your car, the GROM-CAR Bluetooth connection is available for pairing for 3 minutes.

    Thank you.
  • edited June 2017
    I went ahead and submitted a ticket.

    The usb stopped working last night, but after taking the dash apart and unplugging and replugging it in tonight the usb works, but still no Bluetooth.
  • Howdy! Your post seems similar to my own Volvo setup using USB3 and HU-650. When I initially installed the unit, the phone paired fine and USB worked...until I turned off the key. When the unit was powered on the next time, there was no Bluetooth or USB functions. The only way to get things working again was to disconnect the car battery. I was really disappointed in the overall ease of install and use compared to the unit I was replacing. The previous unit only provided iPod connectivity but no USB or hands free functions.

    I reached out to Tech Support here at Grom and was told to flash a lower version firmware. My unit was shipped from the factory with firmware v.50 and the tech recommended me to flash v.49. 

    You can confirm the current version of the unit by powering on without a USB stick connected. Your stereo should show "Track 50" where 50 is the version number. After disconnecting and reconnecting the car battery and following the firmware update process outlined here at Grom, my unit now shows "Track 49".

    Since the flash, my unit has been working better for the most part and remains connected to both my iPhone and my connected iPod. I am tempted to flash v.50 back to the unit to see if the issue will reappear since I would like to take advantage of the improvements noted in the changelog but perhaps I will wait for the next update instead. 

    Once you get everything connected and working consistently, don't forget to add the USB3 config file to your USB stick or iPod and set the music volume level to be the same as your AM/FM radio when changing sources. If using the hands-free Bluetooth adapter, also set the microphone gain as needed (I had to use level 15 and could use 1-2 more) and set your phone volume to 1-2 clicks just below max volume. This will allow for good phone volume/Bluetooth audio and it won't blast your ears when the call ends and the music resumes. 

    Hope this helps. Be sure to post your results here!
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