Here is the Tech Tip - T-TT-0516-18, Just for reference...
Toyota service had to do the same thing, when my digital temp control was off by 20+ degrees.

 

Interesting. Thanks Bll

 

I am now having the same issue on my new (to me) 2019 Highlander Hybrid Limited Platinum. It worked last week when I first tested the car and made a call, but after picking up the vehicle yesterday, no one can hear me when making or receiving a call. My vehicle is long out of warranty, but Bluetooth is pretty useless with all calls muted!

I will try disconnecting the battery for 30 minutes and see if that helps.

 

I realize I never updated my post. I disconnected the battery, which for the Hybrid model, is in the rear compartment. I saw a YouTube video discussing the same about disconnecting the battery to fix the microphone issue. The YouTube poster suggested to leave the battery disconnect at least 30 minutes (or even longer). I left it disconnected for about an hour.

Reconnected the battery and tested a Bluetooth call via the Highlander. Everything working again and has worked since. Problem solved for me -- thanks for posting about this issue!

 

I'm having the same issue with my 2019 Toyota Corolla hybrid. The microphone suddenly stopped working. My vehicle is just out of warranty by 2 months! Took it in to Toyota and they quoted me £2000 to fix saying they'll need to replace some chip! I might try this solution and see if it works for me. How do I disconnect the battery?

 

ook it in to Toyota and they quoted me £2000 to fix saying they'll need to replace some chip!

That's absurd. You can replace the whole system with a BETTER aftermarket system for less then that.

 

My microphone wasn't working (Toyota Corolla hybrid, 2020). The mechanic disconnected the battery for 10 seconds (not 30--60 mins) and reconnected. Problem fixed. He wouldn't take any money. The Toyota dealer wanted $180 to put their tester on it, then who knows how much more. Dealers considered dangerous.