Factory stereo designed to draw main power from ACC?

[91Beater]

I replaced failing after market with another after market.

One thing I noticed is that in Legacy, hot +12v is behind 10A fuse shared with interior lights.
So, modest base actually makes the interior lights flicker

I noticed that ACC +12v is behind 15A RADIO fuse and there are two ACC+12v in factory harness.

The aftermarket uses 18AWG for 12v hot, and 20awg for ACC 12V. The ACC 12v is only used to signal on/off, so the stereo only uses it for signaling purpose.


Was the factory one setup to use hot 12v only for clock keeping and ACC 12v to provide running power?

The ground wire looks wimpy too. It looks like I'll have to pull a a fresh 12v line to stereo.

[Legacy777]

I don't see anything in the wiring diagrams that would indicate the constant & switched were used differently. There were two taps for the switched lead....but not sure why.

http://www.main.experiencetherave.com/s ... iodiag.jpg

[91Beater]

I don't see anything in the wiring diagrams that would indicate the constant & switched were used differently. There were two taps for the switched lead....but not sure why.

http://www.main.experiencetherave.com/s ... iodiag.jpg

Just through reasoning.
Constant is fed from MB-8 which is fed through 10A fuse 25 in the hood.
See the first page on wiring diagram PDF on your site. It is shared with all of interior lighting.

FB-13 is a dedicated power supply to radio from 15A Fuse #17 in interior fuse box.

This leads me to believe factory radio uses constant on for keeping time and memory but pulls power from switched.

The Sony unit I have now has a thick wire for constant on. I think it uses constant for everything and switched for power on/off signal.

So, the aftermarket radio is actually drawing power off of what Subaru didn't design to draw power from.

[Legacy777]

I just looked at the circuit list, and agree with you. The radio is the only thing listed on FB-13.

I would just run a new constant lead. I think I did this several years ago.