Caliper replacement...

It looks like I have a stuck rear caliper on my 2022 Prius Prime. It's barely stuck ... I've notice a decrease in mileage and thought it was the tire change, but I'm not so sure now. lol The rotor is clearly munched with the typical stuck caliper gouging and scoring, but I haven't actually taken it apart to see what's what. On any of the other vehicles I worked on for the last decades this would be a stuck caliper, dead certain.

I've been scouring the web for info on this, and it looks like here is the only place such info exists. I found other Toyota forums, but nothing about caliper replacement. Here, Mendel Leisk put some manual pages up and they are very informative, but they also say to *drain* the brake fluid, which seems ill advised without a TechStream to fix the air problem. I've seen lots on replacing pads here but not much on calipers. As I've been driving the car for months like this, I'm loath to risk making it unusable because I got air in the lines, which is impossible to prevent if the caliper is completely removed.

So far I have this for a process:

1. Keep the fob/key far far away, like maybe where Fiona was born. lol
2. Disconnect the 12v battery.
3. Maybe remove the ABS relay, although I don't see how that matters without the 12v battery this seems like cheap insurance.
4. Pump the brakes before starting 'to empty the accumulator' according to the manual pages.
5. Do the work As I expect to be removing at least one caliper I don't know how to prevent air from getting all the way back to the master cylinder. Even if I plug the line, which I've never done on any other car, there's no way to prevent the heavier brake fluid from pushing a bubble too far. Truthfully it may be a non-issue, as air in the master on a regular vehicle is also Not Good (tm) and that's never happened. I'd love to hear I'm making a mountain out of a mole hill!
6. Bleed/flush brake fluid per normal, ie, pump brakes/vac tool and watch the fluid level. I'll do all four to "flush" as it's never been done afaik. This should also manually repressurize the system, as even if I use a vac tool I'll pump the pedal to be sure it feels right.
7. Reassemble (relay, battery, tires, blah blah)
8. Am I done? I've seen mention of opening and closing the fuel lid and driving in a straight line at 22mph for 5 seconds, though the latter is likely to occur by happenstance while I'm doing a brake check.

Be nice to have a how-to in the main section that explains the procedure, to hopefully avoid that obtuse egregiously customer hostile TechStream madness.

Thanks for your time!...
- Rags

 

Thanks ColoradoBoo! The driver's door is even an issue with the 12v battery disconnected? I've also heard moving the rotors could be an issue, but again I'd expect no 12v would prevent that problem as well, if it even is one. Not that I can replace a rotor without moving it. lol I'm not used to even having to worry about what's on and what isn't, or where the key is, or what door may open. (wry grin) I know this has a sophisticated braking system, so it's not surprising, simply nothing I've ever had to concern myself with. Don't want solvable ignorance causing problems.

I'm more than a bit puzzled at the short time frame myself. The old 2005 never had caliper issues. (shrug) First time I can call it randomness. If it happens again I'm going to be less accepting. (grin)

But it sounds like I may have a reasonable clue what to do to minimize fallout and perhaps even have it Just Work! (tm)

Thanks again...
- Rags