Car won't turn off after installing aftermarket head unit

I would guess that there is some kind of connection between the always on 12V line and the switched 12V line that causes power to be fed to the car. Try unplugging the new head unit and see what happens.

 

You may not have mixed them up, per a wiring diagram, but maybe the wiring diagram is wrong. My suggestion is to use a multimeter and check line voltage on all the wires with the ignition on and off. I'll bet your switched wire is mistakenly labeled and is actually a constant +12. Plan B, you could run a new switched wire from a known source that does turn off - the power feed to the cigarette lighter for instance.

Lastly I've heard of circumstances where a large capacitor fed the stereo and amps after power was off. Do you have that equipment in the system too?

 

After installing the same after market radio system im having a very similar problem. The jvc radio wasn't shutting off on its own, so I manually shut it off. The car then beeped at me as I try to leave and wouldn't lock. When I went back to the prius the next morning the battery was dead.

It seems that the prius power system will not shut off fully after the new radio installation.
Has anyone solved this issue? Can I reset the computer somehow to work with the new radio system?

 

Did you ever solve this? My 2011 with my pioneer is having the exact same issue.

 

Bumping this thread as I had this issue with my 2010 Prius non-JBL HE and been scouring this forum, Reddit and YouTube for answers. Essentially, the issue for me was an aftermarket add-on that didn’t to be as such—found this out while on my 3 hr. Phone call with Crutchfield. I had an older 16 pin connector for an old iPhone/iPod added in my glove box (a Toyota product). According to Crutchfield info, this “dealer add-on” most likely offered at the time. Given I purchased the car (certified from a local dealership) I had no clue it was an add-on. In order to connect, this product has a t-harness connected to the 12 pin connector (unused with the wiring harness I purchased). Once I removed this product’s t-harness no issue and no problem with the car staying in accessory mode. I’ll try and make a post with some tags for others, but I’m guessing this is the culprit for many people when adding this to their 2010 (or older) Prius as the iPhone/iPod connector looks to be a factory install, but is connected behind the HE with zip ties and connector was wrapped with a electrical tape rather than ribbon like other connectors.