Bluetooth Car Disconnects :(

Question

Having a pretty irritating issue with my bluetooth connection and my car. The phone will connect up no problem, but as soon as you try to play a track, switch apps or sometimes even unlock the phone, it'll say the device has disconnected, with a few caveats.

Details;

• Device is a Nexus 4 (The LG One), Rooted running an official rom of 5.1.1, i haven't run any updates or updated any apps in the past week since this issue cropped up randomly one morning.
• Car is a Ford Fiesta, built in 2015, UK 15 plate. I'm connecting my phone to the built in Ford SYNC system, had no issues with it before on the same device

What i've tried;

• Full factory reset on phone
• Installed same ROM again from google
• Full Dalvik cache wipe
• Full factory reset via CWM recovery and via TWRP before flashing roms (Separate occasions)
• "Factory Reset" in car
• "Master Reset" in car (that cleared all my audio preferences for the radio)
• Remove pairing from car and phone and repair (connecting from phone first)
• Remove pairing from car and phone and repair (connecting from car first)
• Allowing car to access contacts, messages and phone audio
• Allowing car to access nothing but media audio

I'm truly at my wit's end here it's driving me absolutely insane, and it only started randomly last week.

What's weird, is that my phone will connect up no problem, the SYNC system on the car will tell me my phone's connected, but as soon as i go to play music, switch apps or unlock my phone, it'll tell me it's disconnected. What's REALLY weird though is that my car will still give me a reading of my phone's signal strength and battery level, even when it's apparently disconnected, and it seems pretty accurate as well.

Just thought i'd run this by you guys incase there's something blatantly obvious i've missed before i head into the Ford garage and start whining at them

Answer 1

So an update for anyone who's stumbled across this question in future;

I think I've managed to solve the problem. Connection restored and music is playing no problem, I've yet to test phone calls and texts yet though.

It would appear the problem was with SYNC and my text messages, I was using the Google hangouts app previously which is notoriously unreliable on older handsets, installed Google Messenger (their new SMS client) this morning, just tried connecting again during lunch and all seems well and stable.

If you're having disconnects especially with a Nexus 4 and (by chance) Ford SYNC, try force stopping, uninstalling updates and ultimately disabling Google hangouts. I'm going to fully remove the app tonight via ADB but for now the disabled state seems fine.

Answer 2

This is a Ford/Sync problem. I've had my 2015 Fiesta serviced three times since July for Synch bluetooth failures. Once was a hardware failure of the bluetooth module; the other two (and a fourth failure I was able to resolve myself) were exactly what you experience. Ford considers it standard procedure to disconnect the black battery cable for five minutes, then re-enter all your personalizations (vehicle health report settings, 24 hour clock, prompts, ring tone, etc.) and re-pair with the phone whenever this occurs.

If you haven't done so already, you should check that you have the most recent version of the Sync firmware; that added an option deep in the menus (right next to "Master Reset") to "reboot Sync". The last time this problem occurred with my Fiesta, that "reboot Sync" operation fixed it, without having to re-pair or re-enter any settings. Don't get impatient; it takes about two minutes (unlike Master Reset, which takes less than a minute). If it doesn't solve things for you, you've lost nothing but time; if it does, it seems likely it'll work again.