Vios infotainment smartphone connection issue

I have a Vios too, and I had something similar. Though my issue was a bad ground. Have you checked the wiring harness behind the radio? It might be worth a look before you dive too deep.

Interesting, thanks for the hint! Where exactly is the ground located? Is it accessible without dismantling half the dashboard?

On mine, it was behind the head unit, bolted to the chassis near the climate control module. I'd recommend checking the connection there first. A corroded connection there acts like a dam, causing all sorts of electrical gremlins. After that, I would suggest going to the workshop to have it properly analyzed.

Thanks! Found the faulty ground. Indeed it was a corroded connection, cleaned it up and everything is working fine now. Cost me 45€ to fix it. Cheers!