BRZ to FRS Headunit -- no sound

[chi86]

Originally Posted by SVXdc

Technically, on FR-S HUs the HU does still provide that power, but it's via the tiny pin on the AM/FM connector.

Attachment 142399

Some HUs (including OEM ones) will disable the speaker amplifier IC (killing all 4 speaker outputs) if any one of them is shorted. Typically that happens after people do something wrong while replacing speakers or doing something in the doors, but in your case it could be a problem inside the HU.

If I did do something wrong and caused a short and now my speaker amp is disabled, is there a remedy?

[chi86]

Nevermind, I found the solution. In this condition, a short exists in speaker wiring. You have to eliminate the short, then the sound comes back.
In my case, I'd spliced my reverse camera negative into the RF speaker negative by accident instead of head unit negative.