How to confirm a battery pack has been replaced?

The orange fluid in between the ICE and HSD is the inverter coolant. With the car in Ready, pop the top of the coolant tank and check for agitation (good sign). Sounds like you are comfortable doing a lot of work yourself so you might be interested in this site:

PriusDIY.com: The Toyota Prius DIY Resource

Congrats, good luck, and welcome to the world of Hybrids!

 

The grinding noise with low speed braking is rusty rotors, common on the Prius because they are used so little. Try braking a few times from 50mph (no more) quickly in neutral. This will force the car to use the discs to stop instead of regen, and will clean up the discs/rotors. If it does not new or machined rotors is the cure.

 

Orange is quite the rage in coolant these days. That location is a separate cooling system which serves the inverter. The forum tells us that there should be movement in that visible bottle anytime the car is "on", which indicates a functioning "inverter coolant pump".

My own question is whether this gallon (which I have) of orange General Motors spec coolant is suitable for the Toyota. I can't see the level in my main reservoir and while the season indicates no likely heating issues, one can't really know how much is in there without seeing the level.

I've had my '04 for three months and have seen the average mileage rise from around 52 to almost 55. Of course, the onset of cooler weather will soon turn the numbers in the opposite direction. I'm thrilled that economy this good can be had in a relatively large and comfortable car. I had over 70 MPG in my 1st generation manual shift Insight but it was much smaller, less comfortable, and very noisy, by comparison. Plus, I wanted all of the top-of-the-line features available only on Toyota's version of a hybrid. I disparaged "drive by wire" and keyless entry (SKS, that is) for years and now I are one.

 

FWIW, If I had doubts about the quality of the car I'd take it to the local Toyota hybrid specialist. Don't worry about the color of oil, or the color of the coolent - they can check the resistance of each module in the traction pack and let you know what you are getting. Sure - you may pay hundreds for an extra comprehensive test - but it'll be way less likely that you miss anything serious on the horizon, when it comes repairs.