2002 Prius ABS problem.

Some diagnostic codes on a Prius don't get picked up by readers other than the Toyota Techstream software, just because the car has more computers in it to query for codes than most readers know about, and (especially in Gen 1) they are connected by several different comms buses. I'm kind of surprised you didn't get brake codes on a generic reader, but not hugely surprised. That's why there's the paper clip method, so you can start getting the basic codes anyway.

But you need to mention which dash light was blinking each of those 52, 56, 58 codes; it makes a difference.

Then, the place to look the codes up is in the Repair Manual (more info).

 

When the ABS light is on and the alarm is squealing is the brake pedal hard and unresponsive? When my 02 did that, it turned out that the brake booster pump motor was failing or failed. From Toyota it's a $1000 assembly. I replaced mine with a used one from the wrecking yard. It's a real knuckle buster to get out and then back in. But it solved the problem for the past 2 years and 8 thousand miles. I know where there are a couple of junk yard ones, if you can't find one in Kansas, we might be able to work something out. As I remember, the codes cleared out by themselves when the brakes were fixed. Pump assembly is in the vicinity of the brake reservoir, look it up on google and you can get a picture of the assembly.

 

Have you had a chance to look up the 52, 56, and 58 you had blinking on your ABS light yet?

52 and 56 are related to the ability of the pump and accumulator to build and hold brake pressure: 52 reports that the pump has been running a crazy long time (5 minutes!) without building the expected pressure, and 56 reports signals from the low-pressure switch that aren't what the ECU expects (56 has a detection condition with five alternative branches, covering most possible weird cases like the switch being stuck and therefore low and high pressure signals seen at the same time, or low pressure for an unreasonable time, a minute or more, etc.).

There are seven and six pages in the manual, respectively, of troubleshooting steps to pin down the cause(s) of those codes, which could lead you to replacing the pump/accumulator assembly. (There's a member here, rlin78, who worked out a way it can be done without having to evacuate and recharge the air conditioning, but reported it took about ten hours that way.)

But before getting too deep into that, there's that code 58, which is, umm, the low brake fluid level warning. That would be worth following up on, because that could certainly lead to inability to pump up fluid pressure and thus to the other two codes.

If you're sure the fluid level hasn't been low, then it indicates a problem with the level switch or wiring.

If it did get low enough ever for the pump to suck air, the system will have to be thoroughly bled, best using the utility in Techstream, because the air will be in the head-end components, not just down at the wheel cylinders where it's easy to let out.

 

Nice response, Chap.

 

The solid source is the repair manual for the car.

If the 'anything' in question is the repair manual access at techinfo.toyota.com, it will be actually the information you need.

I find the clunkiness of its register/login interface to be really the bigger annoyance than the $20 subscription rate; if one imagined paying other PriusChatters a going rate for help given for free, $20 would burn up pretty fast.

 

They wouldn't have the manuals at the library. You can look up the codes on the internet, in your search terms be sure to include "Prius" and the model year plus the code which will begin with a 'P'. I can understand your reluctance to invest in the manuals, they are a bit spendy. I think you can get both manuals for about $100, from Berkley Press. RockAuto has one on CD for about $20. Know nothing about it, but I assume that because Rock auto is offering, it is licensed from Toyota. It is in Acrobat format, could I suppose be transferred to a tablet. It's Microsoft and Apple compatible.

 

Elektroingenieur put together a useful wiki page about various ways of getting access to the repair info. Much of it is available in some libraries (usually not in the form of the physical books, but in the form of online access through a service the library pays for).

It is a bit spendy to find the Gen 1 physical books now (which are out of print at the official distributor) but the online access at techinfo.toyota.com is still live.

 

That's the method that's in my notes. But if the condition the codes were reporting is still present ....

 

Thanks! I'm of a certain age, where the appeal of social media and tied-in "walled garden" forums hasn't ever made much sense to me. I even think this forum is kind of a soup sandwich for finding information, compared to a well-used wiki, where something could just get written once and improved over time, instead of everything having to be endlessly repeated in new threads where somebody hasn't found the old ones.

But for some reason the PriusChat crowd hasn't really caught the wiki bug, even though there is one here with some good information on it. (The XenForo wiki software doesn't win any awards in my book ... even the "table of contents" doesn't seem up to date, except right after somebody manually updates it.)

As for other things to check, I can't think of much to add to the troubleshooting steps in the manual, where you would be checking for some basic wiring or connection issues, before replacing the accumulator assembly. I imagine it would be frustrating to to put in the work of swapping that and find the problem was still there, and then to find the real cause was something maybe less work to fix. But that would take going through the suggested steps.

 

This should be a pic of the whole pump/accumulator assembly:



It appears to me that what your sister ordered is the actuator assembly (it is so fn easy to mix up the words ac·tu·a·tor and ac·cum·ul·a·tor).



Before you get too disappointed about that, it's still possible you have the part you need. When you have codes about the ac·cum·ul·a·tor not being able to reach/sustain pressure, and you're not leaving pools of brake fluid behind you, one of the things it can mean (if you hear the pump running) is an internal leak, where the fluid gets past a valve that's supposed to be normally closed, and returns to the reservoir. That can happen all in the ac·cum·ul·a·tor assembly, but in fact most of the valves in the system are in the ac·tu·a·tor assembly. So if you do have an internal leak, and you haven't yet pinpointed it to know which of the two assemblies it is in, then you still have a chance that the part you have is the one you'll end up needing.

 

The actuator might be a bit more straightforward as far as that goes. The cowl, inverter, and HVAC water pump are in the way, but you don't have to fuss with evacuating/recharging the A/C (or doing the ten hour rlin78 shuffle).

I wouldn't undertake either job without Techstream if I could avoid it.

The Gen 1 head-end bleed procedure does seem to be simpler than the later generations. There is only one solenoid in the actuator that you're using Techstream to command open (while holding the brake pedal down) to force the fluid to flush through the head end.

Back when I had a Gen 1 and no Techstream, I always had in the back of my mind that if I absolutely had to, I could probably find the pins in the wiring diagram for that one solenoid and hot-wire my way through a bleed process if I absolutely had to. (Never more than 2 seconds of power to any ABS solenoid, with 20 seconds to cool in between.) But I never ended up absolutely having to, and it would take absolute necessity to make me go there.

You'd already want Techstream for diagnosing problems like this, and future others, anyway, and it makes everything easier.

By the way, the manual notes that those 4 connectors you see on the side of the actuator are actually not different shapes (the way nearby connectors nearly always are, so you can't goof reconnecting them!), so you have to note the wire colors when reconnecting.

I'd probably keep the new part and the tools on the shelf a bit longer and see what more information can be gathered about the problem. The ECU monitors the operation of the pump quite extensively, so if the codes come back, Techstream should be able to give you a wealth of information (when you include the subcodes and freeze-frame data) about what's going on.

One of the codes you had requires 5 minutes (!) of the pump running without achieving the target pressure (which normally takes but a second or so). If that code comes back, an easy observation would be: did anybody even hear the pump during those 5 minutes? Maybe you have an intermittent electrical supply issue. Sometimes, not always, that can be in the pump motor itself, if the carbon brushes are worn, and the motor happened to stop last time in a spot they don't contact well. If it isn't running, will it start if you bang something? Because of the monitoring I described in the link above, Techstream can point you to which part of the circuit to focus on.

Not large, in my view; not zero. If there's a particle of grot sometimes preventing a valve from seating, possibly just the ritual of fluid changing would dislodge that as a side effect. So might also the ritual of head-end bleeding, without necessarily even opening any bleed ports.

I would stay focused on getting a handle on what's happening.

In another thread a week ago, I had 'explained' to me how a 'good mechanic' has 'refined instincts' on what to go tearing into before the facts are in, and so can avoid "car repair distractions" (apparently = diagnosis) in favor of "just getting it fixed with as little effort as possible" (= awesome if the person paying your time and materials isn't you).

Situations like this reveal why I haven't come around to that way of thinking.

 

Where are you located. I live in Wichita and have a laptop with Techstream. We own an ‘03. Maybe I can be of some help. Let me know.