Parking brake was stuck for a moment

Nothing It's just happening in the freezing cold generally parking brakes don't really stick sometimes they freeze but as soon as you move the car two or 300 ft and the rubbing of the brakes starts to heat up the system very quickly unfreezes and releases I haven't used my parking brake in any of the four Prius that I own in years sometimes I'll step on it and release it step on it and release it step on it and release it in hopes of adjusting the rear shoes a little bit with the adjusters but usually I just wind up using a brake spoon and cranking up on them one or two clicks every year or so you won't find much back there to fix The cable and all that usually doesn't really get stuck there are a couple of points where you can add some lubrication but unless you're in some serious kind of climate I wouldn't think it would ever be needed but then again I'm in a very temperate climate on purpose so that I don't have a lot of weather related goings on with my vehicles and other things.

 

I would use it more. Apply/release it a bunch of times even, whenever you get in the car. Sounds like previous owner didn’t, and it’s getting rusty or jammed.

 

Some info from Repair Manual. Not sure if there's any maintenance suggested. A few shots of WD40 might help, if you can find places to squirt into the cable sheathing. It's very thin, mostly solvent, with a bit of lubricant. Helps drive out moisture, might flush out gunk.

There's mention of travel adjustment.

Geez, I see step one of removal is to discharge refrigerant??

 

My parking brake wasn't holding on a steep slope (a ramp in a nearby parking lot). We took the drums off and found a ton of dust in them but no other obvious problems. After cleaning that out, we put the drums back on. Then adjusted the rear brakes by applying the parking brake and releasing it a bunch of times. (There is a gear mechanism in the rear brakes,which if the spacing is too wide, pull them in a notch on each parking brake application. If the spacing is not too wide applying the parking brake adjusts nothing.) After that the parking brakes would hold on that slope.

If the parking brakes are never applied it is likely that the rear brakes are not adjusted properly.

I have lived in too many hilly places to ever park a car without engaging the parking brake. Yeah, I'm also the guy who curbs the wheels even on a gentle slope.

 

Just applying and releasing the parking brake a bunch of times might not be effective for everybody; if it worked for you, your adjusters must have been pretty new or super easy-moving.

I describe it as more of a ONE-TWO action: ONE, you apply and release the parking brake. When you apply (if the shoe-to-drum clearance is more than 0.03 mm), a spring-loaded lever gets cocked one tooth up on the star wheel.

TWO, you apply and release the regular foot brake. That spreads the shoes and takes the tension off the adjuster, so the cocked adjust lever is able to rotate the star wheel down by that one notch.

So you can quite reliably adjust by repeating that ONE-TWO a bunch of times. (If you are in a quiet-enough place, you can hear the click of the adjust lever on ONE; when you stop hearing it, adjustment has been achieved.)

If you leave out the TWOs and just repeat ONE ONE ONE ONE, you only succeed if the brake parts are so very free-moving that the adjust lever is able to rotate the star wheel down as you release the parking brake, even though the shoe return spring tension is still on it. That seems to have worked in your case, but I think that's rare.

 

I believe you. Maybe it worked because we had just cleaned all the dust out of the rear brakes (including blowing it out) with the drums off and that let them adjust more easily?

A lot of cars are designed to adjust the rear brakes by some normal driving pattern. So the owner won't have to remember to adjust them. For instance, backing up and stopping often does it. The Prius doesn't do that, but most of them probably go through his cycle at least once every 24 hours:

1. parking brake applied (park car)
2. brake is applied (car to be restarted, go to READY)
3. parking brake released, brake still engaged (prepare to drive)
4. brake released (drive)

Should that adjust the rear brakes?

 

Yes ... having the brake applied while the parking brake is released means there isn't return-spring tension on the adjuster, so it can expand easily enough and the star wheel can turn.

 

Interesting. Since the rear brakes on our car were not adjusted properly (parking brake would not hold a slope), and the car was put through the 1,2,3,4 cycle frequently, something was preventing that adjustment. All we did to resolve this is clean out the dust, which suggests that the adjustment mechanism can get clogged with enough dust to make it inoperable.

On normally functioning Prius rear brakes, how much dust should one see when the drum is removed? We have not had to replace the pads on ours, maybe a previous owner put on some particularly dusty material?

 

It can. Also, you can find, if it has been stuck that way a long time, that one or two teeth on the star wheel are worn down to nubbins where the adjust lever has been clicking up and down over them endlessly without rotating the wheel.

Naturally, such an adjuster is never going to work right again even if you get it nice and clean. But replacements are just a few bucks.