Gen 2 Brake Problems

Must be out west I guess United States is a big place I love it when people don't give their basic geographical area makes a lot of things sink up very quickly for some but it must be an out west thing because I sure don't hear about a lot about this on the East Coast so it must just be a thing that happens a lot out west Nice roads rats beavers God knows what else just eating up the wiring because it tastes so good and Prius vehicles seemingly especially a few terrains that I know of that's a Chevrolet thing that's about it that's really wild yeah your brakes come back to the vehicle skid control module sometimes so some people have replaced that with good luck there's also a barrage of tests you can run through that will take hours and you'll need to get it the computers behind the glove box and what have you so you've got lots of trouble shooting with the DVOM to do and you might want to look at getting a some kind of copy of TIS.

 

We have a post where a member kindly reviewed several from quite cheap to more expensive, outlining the capabilities of each.

It would be very helpful to have the actual codes. I have my doubts about the one they said was a brake stroke sensor error is correct. In addition, the one the said they couldn't specify because it couldn't be read in detail might be a key code.

 

A failing ABS module causes alot of problems. At 200k, that's around the time it usually fails. The good news is that Prius parts are generally cheaper(around $500)

 

Current rates if you don't buy this part on the internet that you're discussing above it's about $1,763 at your Toyota dealer and they won't have it. If you order it online like my buddy did about 3 weeks ago and pick it up at the said dealer it's about $1,284 I believe I'll have a copy of the receipt right here considering what other ABS cars like the 2016 and up Corolla and Camry that part is $150 remanufactured all day long and many shops can remanufacture it It's not like there's a supply problem this thing in the generation 2 and the generation 3 Prius is built like early ABS or mid ABS that was in BMWs and high-end European cars where every park cost at least three or $4,000 way back then now of course they can't charge that. And in all this time that's passed we have learned how to make these parts properly efficiently and inexpensively. So the parts that are on the Prius are like the early ABS parts that folks didn't really understand well yet and you remember all the BS about ABS brakes back in the day and if you don't well it doesn't matter. But to a person with a 04 to '09 car a 12 to $1,700 brake part just for one part and the $3,000 or $1,800 catalytic converter which for most cars is about $80 is quite something to stomach to get 12 more miles to the gallon over your Yaris. To a lot of people those kind of repairs hurt I get it luckily I usually buy my ABS pumps and nonsense used off cars that don't have the light on and all that sort of thing so far I've been lucky I haven't had to change one 6 to 10 weeks or a day after I install it but it's an easy job I can do it quickly it just takes a couple hours on a Saturday morning or whatever morning. But I do understand how these cars are falling into the junk yards now at record rates insurance companies and what have you as soon as one of these things get a dent in the rear bumper boom off to LKQ. I just bought a car headed for LKQ and what have you couple weeks ago for like $600 $700 didn't need anything but a jump The battery I guess the HV one isn't squat so I'm taking care of it but the rest of the car is mint a few scratches but who cares.

 

I think the ABS module failure is pinpointed to the dc motor and the accumulator. Not sure how the alum bloc holds up. The DC motor is easier to rebuild since DC motors are a dime a dozen. The correct brushings is an issue. The more difficult part to obtain is the accumulator. I think there are aftermarket accumulators but I'm not sure how they fair.

 

In Gen 3, the common issue seems more to be internal leakage. Some valve isn't holding perfectly sealed, and the accumulator doesn't hold pressure and the pump has to run a lot, not so much because of anything wrong with the accumulator or the pump, just because the fluid is sneaking back to the reservoir.

Of course, once that starts happening, the extra frequent cycling yuugely accelerates wear on the accumulator and pump, too.

 

Yeah there was a guy on eBay that claimed he could rebuild these things had a whole test rig set up in a shop and everything I guess the test rig could be set up to work on other ABS pump systems too It look like a pretty good size rig but I don't know how you would open and close the valves internally I guess with the software so maybe for rebuilders as a universal software that will work almost any kind of break valve and so on and so forth maybe something to look into. The two that I managed to get from the guy both installed on cars and have been working perfectly I can't get in contact with the guy to pay him for the other one He just vanished.

 

Our accumulators are filled with a shot of nitrogen and the very heavy shot when you take one of these out and take it out of service You're supposed to drill at the point shown in the manual at the bottom of the accumulator this releases the gas won't hurt you just releases the gas now you can unscrew the accumulator off of the aluminum block but I don't know that. You're going to be able to get a replacement accumulator like that type of thing I kind of doubt it but maybe I don't know if there's a way they can put the gas in there and then when you screw it onto the aluminum block it does its thing or how that works. But there again it's probably similar to the Gen 3 there's something internally leaking causing it to run all the time like it does in the Gen 2 and well there you go.

 

Yes I just don't see how the accumulators can be rebuilt.

 

There's a thread here where somebody did find a source for an accumulator about the right size and threading, and replaced it. I remember seeing the thread. But I don't remember seeing a lot of threads like it.

 

So I guess the thing could ship with nitrogen in it and have some kind of breakaway device when you screw it on to the aluminum block or the whole assembly and then the nitrogen releases itself and goes into where it needs to go or something I don't think it's added after the fact or the new one wouldn't have the nitrogen. Would seemingly be kind of strange but it certainly removable I guess you ought to have the thing drilled in the gas out trying to take it off with the gas still then it'll probably blow off the end of the aluminum like mortar fire but probably wouldn't go I don't know 3 ft I'd try it behind my engine lathes protective shield guard aimed at wall.

 

It doesn't need any kind of breakaway device; there's a sealed bellows inside it and all the nitrogen is supposed to stay on one side of that.

Sometimes the bellows will spring a small leak and then you get nitrogen bubbles in your brake fluid. That's not something you want, it only happens if the bellows leaks.

When the pump shoves brake fluid into the accumulator, it pushes the bellows up against the nitrogen pressure. When the brakes are used, the nitrogen pressure behind the bellows forces the fluid out, but the nitrogen stays put.

If you unscrew an accumulator without zeroing down the system first, you will launch it across the room on a jet of 2000 psi brake fluid, but not on a jet of nitrogen. (Unless there's a bellows leak. But those are usually small, so it would probably fly across the room on a jet of brake fluid and then sit there quietly going sssssssssssss.)

You drill the hole to let the gas out for disposal so it won't be a bomb for the trash guys if they crush it, or it sits and the landfill and rusts.

Oh, the other thing about unscrewing it under pressure ... maybe more likely than flying across the room, you start getting thin jets of 2000 psi brake fluid squirting around the threads first. Not good; high pressure fluid jets can do the Star Trek hypodermic injection thing for real, but it's bad news. If not treated very promptly, amputation can be called for.

 

Well that's good to know there's a bellows and it's sealed supposedly on one side so you can just put a towel around it to catch the brake fluid if I was interested in taking it apart which I don't think so so then people have found new accumulators the nitrogen type and all that just to replace? That seems pretty interesting seems to me the valves inside the aluminum block or what the holdup usually is piece of crap gets in there It doesn't allow the valve to close or what have you and or doesn't close enough and it's constantly peeing brake fluid and hence you hear your pump running. It really sucks because like 4 years later and all this went down the proverbial toilet now these accumulator pump assemblies are mounted on the fender well and yada yada blah blah blah and they are inexpensive to buy rebuilt and very or so it seems anyway.