Sometimes the Toyota RAV4 (for example, the 2021 plug-in hybrid) refuses to connect to a phone, showing the error message "USB Error" or "USB device not recognized".
Symtoms
When the phone is connected, you hear the charging sound—then it stops. A second later, the sound returns. Then again. And again.
On the display, you'll see messages like "USB Error" or "USB device not recognized".
Possible Cause
One possible explanation is that the phone is overloading the car’s USB port.
In my case, a Xiaomi phone with a "Turbo charge" mode appears to trigger this issue. My guess is that the phone attempts to draw too much current when connecting, causing the car's system to disconnect the USB device. This cycle then repeats endlessly.
Suggested solution
This workaround is still under testing, but it has worked consistently so far.
The idea is to limit the current draw from the USB port to around 500 mA by inserting a 10 ohm resistor in the +5 V power line.
Step-by-step:
-
Purchase a basic USB hub, such as the AXFEE 3-port USB 3.0 hub (available on Amazon, Temu, or AliExpress).
-
Open the hub casing. (There are no screws—it's held together by plastic clips. Use a knife or spudger to gently pry it apart.)
-
Remove the PCB (circuit board) and locate the power trace (as shown below, indicated by the blue arrow).
-
Cut the trace, and solder a 10 ohm resistor in place.
-
This will limit the charging capacity from both the USB2 ports (the black ones) while still having the normal behavior in the USB3 port (blue).
-
(In theory, it might work even without a resistor—but then the phone likely wouldn’t charge at all. Our goal here is connection, not charging.)
-
-
Reassemble the hub and connect it to the car’s USB port (the one in front of the gear shifter).
-
Connect your phone to one of the black USB 2.0 ports on the hub.
-
The blue port (USB 3.0) will remain unaffected and can be used normally.
-
Another completely different solution is to modify a USB2 (extension) cable. If you split up the cable, the red wire is usually the +5V. You can simply cut it and see if it works, or solder a 10R resistor in series.
Another suggested trick is to put some plastic tape over the trace carrying +5V in a USB2 (extension) cable connector. I haven't tried that and in my case I'd probably curse a lot when by mistake trying to use it to charge the phone.
Expected result
When connected via this modified USB hub, the phone should start Android Auto as intended—but it may not charge.
Note: Be aware that the phone may slowly discharge during use. Use a different USB port or charger if you need to charge it while driving.