2003 prius squealing. Stops with brake pedal

Hello! Im a relatively new prius convert.
I have 2 classics. One is almost flawless, and the second i bought as almost a basket case. It has some front end damage,basically cosmetic.
The previous owner said it needed an inverter...and the hybrid battery was toast. I finally found a gen1 battery for a decent price($350!). And it was only a 1050 mile trip in my dads prius to pick it up. It only needed one module(so far).
I finally got it drivable and i get a bad squealing noise that seems to come from in front of the driver. If i tap the brakes it will stop then start. Tapping repeatedly works best. This noise occurs at ready when the car is not moving. Ice doesnt need to be running. I kept tapping the brakes to get it to stop while pulling codes.
Any ideas?
Thanks.

 

What bearings? The car isnt moving and the ice isnt on.

 

Well, it had some variety of codes. Maf was dirty, and it kept telling me modules 6 was out. Im still working on the battery, got the module ordered and am trying to cycle the others on the bench. So currently the car isnt running again. But it will be.
The squealing sounds like an electric motor with bad bearings. Sometimes it would come back even when i kept the pedal pushed, hence why i started tapping them. I did have brake light and abs light on at first, then they went away after a little driving. I have probably driven it about 5 miles total. I did change the inverter (the car came with two extras). Noise was there with both.
It also made this noise when we first tried to start the car when it had only 12v power( the traction battery was about 0 volts).

 

Thanks on the pull apart. I think the previous owner worked at a scrap yard or something.
The noise does come from under the hood. I was thinking it might be brake master cylinder related because the noise would stop when i would step on the pedal. But then it would start again. I cant remember if it did it while driving or not. It seems loud for the inverter pump motor but its possible.

 

My replacement battery module showed up today, once i get that replaced and the battery back in i should have her up and squealing again. I will be able to continue diagnostics then. I really didnt get a good chance to listen with the hood up. First time i heard it, i thought one of the mg motors was spinning on a shaft or something.

 

I replaced my bad battery module and cleaned half of my battery bars....what a complete PITA !!!! But so far so good except for the squealing.... The brakes and abs light came on ,along with the annoying buzzer to let me know the warning lights were on. I could feel the abs assembly and im pretty sure thats where its coming from . does the abs module require wd40,or duct tape, or replacement.?
At least im pretty sure i have a good gen1 hybrid battery now. This car also needs a deep shampoo,front bumper and cover,ac work,and a front windshield (and the abs). I may end up keeping this for parts and moving my hybrid pack to a better car.

 

Ive driven it a few more miles. This car sat for some time and that might have had aomething to do with the squealing.
For now it has stopped. I did get 2 tires on the dirt and 2 on the asphalt and hit the brakes pretty hard to make the abs do something. I did it on each side. The abs seemed to work. Regular driving the brakes work fine.
Fwiw i was alone on a remote road and did my abs exercises at a safe speed. Didnt get very exciting.
Thanks for the comments. I'll post any updates. Im gonna keep my eye on it but im leaning towards clearing out the cobwebs.

 

My luck didnt hold out. The lights and squealing came back. I havent pulled codes yet with my bluetooth yet. Not sure if it will tell me much. I do have the techstream cable but havent downloaded software yet.
And if you couldnt guess, your user namee prompted mine brian.
Im looking at another gen 1 for cheap right now.its alittle trip but i think it will pay off. I am a super cheap guy...

 

So i changed the abs pump. I havent really got the car quite up and driving but how did you bleed the brakes?( through the abs module) i read a little about using a scanner to cycle the abs to get it to bleed.
Btw. So far my 200 parts prius has yielded a good abs pump,an inverter i feel better about and a good traction battery.

 

I appreciate the offer but i might try to get techstream on my wifes laptop before we head out to Oklahoma city on vacation in 2 weeks. We'LL be in the good prius though.
So you bled yours without cycling the abs solenoids? Ive read that its necessary, but Ive also read a lot of things people say are necessary but arent. I wont be daily driving it until i feel its safe either.

 

I have a couple things to report.
So far so good.. I bled the abs module and the brakes. So far so good. Abs worked and pedal feels good.
I also adjusted the rear brakes on both of mine and they both feel a lot better afterward. The self adjuster imho doesnt seem to work well. I do understand you dont want any drag,particularly on a prius but the brakes seemed to come on rather sudden before and after adjustment they seemed to smooth out. This was on my daily driver.
I adjusted the brakes while i swapped tires around. 4 new lexani 84t 175 65 14s for the daily, at 165 shipped to more door. One of the 4 required about 1/2oz to balance it, the other 3 didnt require any weights at all.
They ride smooth and are more quiet than the harmony/kumho combo i had on before. After only 50 miles or so mileage seems the same. I have a road trip coming up and will report more after that.
Thanks for the helpful advice.