2005 Prius JBL Radio No Sound - Solution

I've had a difficult time trying to find why my radio suddenly stopped putting out sound. I now have a partial solution.

Initially, the radio would show all controls working properly: volume indicator, station indicator, stereo detection, and the radio would properly scan for stations. Based on this behavior, I thought the radio was working properly so it must have been a faulty amplifier. I purchased an amp from an auto salvage place and installed it. No change.

I then took the car to a guy who works on Prius who tried installing a replacement MFD (Multi Function Display) in case that was the source of the problem. No change. Still no sound.

Keep in mind that the speakers work fine for bluetooth and the guidance system. Only the radio output is missing.

Since there was only one component left, I ordered a replacement radio from an auto salvage place and installed it. Still no sound!

At this point, I had replaced all three major components with no improvements, so I took the car to an auto stereo shop that also did diagnostics. They checked every component out and said they were all working and had no shorts. Then the technician had the idea that maybe the radio was on "mute", a state needed to allow the other audio features to temporarily suppress the radio while they made their announcements. He checked the wiring diagram and found the mute wire and sure enough, it was constantly on!

Our solution, one that's not very elegant but works, was to snip the mute wire and install a toggle switch under the dash. Now I can interrupt the mute signal manually.

What I discovered with this new arrangement is that my iPhone Google Maps app works fine over the car speakers. It suppresses the radio somehow when it's time to make an announcement and when the bluetooth signal quiets, the radio resumes. The car guidance, however, now announces right over the radio audio unless I allow the mute line to function by switching the toggle.

So there is some circuitry that is supposed to moderate the mute line that has allowed the line to stay on constantly. We tried disconnecting the battery for a period of time to see if it would reset, but it didn't.

Snipping the line did the trick!

P.S. Anyone want to buy a JBL amp and radio combo? <g>