100,000 mile service

Transmission is only a drain and refill, not a flush. Toyota says it's a lifetime fluid but most of us will change it anyway as it can only be a good thing and is easy to do. I have 52k on mine and will change it this spring as soon as weather permits. I'm not sure about the trip meters retaining what they have when the 12v is changed....even though I changed mine just a few months ago.
I recommend having the EGR valve cleaned as on some gen3s they appear to clog and encourage head gasket failures, although I see many many gen 3's that go over 200k without ever having done anything at all concerning the EGR. You might want to do some research on that.
Good Luck!

 

A drain and refill are all that is necessary. I had my CVT (transmission) WS oil changed at 90K and 180K and planning on 270K when I get there. Some Toyota dealers will say the CVT oil is lifetime, but all you have to do is take a look at what drains out at 90K. The two coolant loops should be drained and refilled every 100K. You might want to get a load test on the 12V battery just to see. But yes, 9 years is a good run. It is possible to keep the volatile vehicle settings (odometer trip A and B, AM/FM radio presets, AUTO power window settings) by attaching a 12V DC source to the electrical system prior to disconnecting the auxiliary 12V battery, but I don't think Toyota dealers will routinely do this. You might ask, or just write everything down. With a vehicle electrical system reset like this the car will have to re-learn how you drive which may result in an initial decrease in MPG.

 

You can save the settings, if you keep 12 volt supplied during the swap. Ask them before you bring it in, if they can manage that.

What I use, is a a memory saver cable, one end plugged into my jump pack, the other plugs into the obd port on the car. The cable has an indicator light to confirm connection.

The memory loss is no big deal though. I intentionally disconnect everything when doing brake work, just to play it safe. You'll lose radio presets, the auto-up function on windows may need to be retaught*, and I believe the trip meters all go back to zero as well.

One other quirk, post disconnect: I've noticed at the next two or three start ups the car will do an unusual rev-up, for about the first 30 seconds, like something is being recalibrated.

* Run the problem window down, then run it up, constantly pulling up on the switch. After the window is fully up, continue to pull up on the switch for at least a couple of seconds more. That should do the trick: test by just tapping up on the window switch, the window should continue all the way up.

 

^ You beat me to recommending that.
Glad it worked out for you.

I concur with others on the CVT fluid replacement. Some Toyota dealerships will do this and others will push back on it.
It's probably about a $120 job. I'd either DIY it (it's not much more complicated than changing the oil) or pay it done by an independent mechanic if the dealer quote is much more than that.
Be sure and use the OEM fluid since your "Transaxle / CVT" has electrical components not normally found in other CVTs.
(it's actually called a power splitter, IIRC)

I'm thinking that coolant replacement periodicity is 120/100,000 for your car - but here's a copy of your maintenance guide.

https://www.toyota.com/t3Portal/document/omms-s/T-MMS-11Prius/pdf/T-MMS-11Prius.pdf


Start thinking about maybe cleaning the EGR cooler and since you live on free soil (ish) maybe an oil catch can.

Many threads on these items.

Good Luck!