Android Wear as a smartwatch operating system is not without its faults, but sadly while the more tech enthusiastic are likely to use it, the same people are also likely to install custom ROMs on their phones. This in most cases means having to wipe your smartwatch every time you switch to another flavor of Android on your device. There is, however, a simple way to bypass setting up your smartwatch from scratch when you buy a new smartphone or flash a new custom ROM on your device. This method does not require root on either the phone or watch, but it does require a few Android Debugging Bridge (ADB) commands. This has been tested on the Huawei Watch on Android Wear 1.5 and Android Wear 2.0, however it should also work to pair Android Wear watches with any new smartphone. If for some reason your watch is already rooted, you can ignore this tutorial and simply use the Reset Wear Client to pair Android Wear without factory resetting directly from your smartwatch.


Pair Android Wear to New/Same Phone Without Wiping

First, you will need to download the ADB tools. I personally use the “Minimal ADB and Fastboot Kit” found right here on XDA, but you are welcome to use the official binaries from Google if you wish. Next, you will need to enable ADB debugging on your smartwatch (both wired or over WiFi debugging are fine, though I find WiFi more convenient). This is enabled through Developer options on your smartwatch, which you will also need to enable. To do this, simply go to Settings → system → about  on your watch and tap the field labeled “Build number” until you see a  toast message stating “you are now a developer”.

Android Wear Reconnect without Factory Reset

Once you have followed these steps, you’re ready to begin!

Enabling ADB debugging

Open Developer options and enable “ADB debugging” or “Debug over wifi” if you wish to do it wirelessly. The process to sync Android Wear to your smartphone will work fine both ways, but they require slightly different commands.

Android Wear Reconnect no Factory Reset

Initial setup to sync Android Wear will require a different command whether you are doing it over WiFi or not. Please open adb tools, either by searching adb in your Windows search bar or navigating to the folder containing adb, holding shift then right clicking and selecting “open command window here”. Then enter the below commands.

Over WiFi

In my case, I would type:

        adb connect 192.168.1.100:5555
    

To connect to my Android Wear watch. The IP address you need to enter is located under “Debug over WiFi”, as shown in the screenshot above. Accept the prompt on the watch allowing the computer to debug. If successful, it will simply go back to the command prompt where you can type. There is now text output.

Wired

Substantially easier in commands, simply connect your device to your computer and type:

        adb devices
    

If your device shows up, you’re fine. Make sure you accepted the prompt on your watch to allow it to debug.

Sending the Commands

To continue on, first disable Bluetooth on your phone and then on your computer type:

        adb shellpm clear com.google.android.gms && reboot
    

Your watch will reboot, but no Android Wear factory reset will occur. When it boots back up it should no longer show a crossed out cloud icon indicating that it can’t connect to your phone. You will now want to install the Android Wear app on your phone (if you don't already have it), but don’t enable Bluetooth yet.

Next, connect to the smartwatch via ADB again with the exact same steps as before. This time however, the command you want to run is:

        adb shellam start -a android.bluetooth.adapter.action.REQUEST_DISCOVERABLE
    

And then on your watch allow it to be discoverable to other devices so you can sync Android Wear with the smartphone. You may now connect to Android Wear from your smartphone by opening the Wear app, enable Bluetooth, and search for devices. Your Android Watch should show up and your phone will sync with it. If the app hangs on “Checking for updates”, simply restart the app and it should begin to connect to Android Wear.


Explanation

The simple explanation as to why this works is that all smartphone-smartwatch pairing data is contained in Google Play Services. This data is phone-specific as the keys are stored in the Play Services data located on the smartwatch. This is the reason why you can’t simply Titanium Backup the Android Wear application from your smartphone, because the keys you need are stored on the smartwatch. When you try to pair a new phone (or have installed a new custom ROM and the watch thinks it's a new phone), the keys are normally wiped through an Android Wear factory reset.

The only way to get around this is to instead wipe the key data which allows you to pair Android Wear with a new device without factory resetting as the keys that pair it to your phone are also cleared. We then request the smartwatch’s Bluetooth to be made discoverable via an intent sent through adb, which creates the prompt you see that needs to be accepted. This means your phone can now find your watch and then create new pairing keys with the device.