ABS and Brake light on. No codes?

See if you can find brake XGAUGE definitions. I'm not sure I remember seeing any. This may be as case where you'll need a TechStream solution like miniVCI. However, Chapman has done some great work in triggering the controllers to flash their codes. Search the forum to find what he has done.

Bob Wilson

 

You're too kind - it's totally, clearly documented right in volume 1 of the manual. Brake controller codes will be blinked out on the ABS light. They are two-digit codes, which you then have to translate to the letter-and-four-digit codes the scanner would give you. There's a table right there in the manual showing both codes.

-Chap

 

You can view/download the Toyota manuals at techinfo.toyota.com for cheap. When you see how to pull the codes, you'll also want to see what they mean and what to do about them, so you'll use your login more than once.

I had a Chilton manual for my first car. Ah, the memories of all the hours I spent figuring out on my own all the stuff that wasn't in it (because somehow, as a teenager, I literally didn't know that the real factory manual was a thing that existed and you could get. A lot like all the hours I spent figuring out chords to songs by ear because I honestly hadn't noticed there was sheet music for sale in the music stores!)

-Chap

 

I don't think the ScanGauge is able to contact the ABS computer - the Gen 1 threw together a handful of computers that speak several different protocols that the ScanGauge can't do all at once or at all. (Gen 2 is simpler because by then everything pretty much speaks CAN.) That's why the only codes it's showing you have nothing to do with the ABS. To see the ABS codes you'll need a Toyota scanner, a Mini-VCI sort of thing, or to use the blink codes.

-Chap

 

My ABS and brake light just came on a few weeks ago. The dealership turned them off and said if they come back on it is indicative of an actuator problem. They came back on and the Toyota dealership wants $2000 to fix the issue. I am not liking this. Any folks out there know of a different approach to this issue?

 

Contact Eric Powers over in Madison WI. He may have some suggestions.

Bob Wilson

 

Hi Bob...or anyone that has had experience with this sorta common problem
gittarpikk in Maryville here....been a while since I posted...but your probably one of a few that could diagnose this..

history...
bought 2002 prius in dec 2015... rebuilt battery in jan 2016... Walmart overfilled oil and ran down main and aux batts in feb
disassembeled main and recharged each module,, replaced aux with walmart garden tractor batt..(works great) and everything fine.
heard brakes grinding...so replaced rear brakes... and later front
all work done by me.
later the abs and brake light came on and squeeling chime started...It would come and go...brake pressure somewhat greater when abs/ brake light on
taped over chime to reduce noise to livable level.


...started getting codes that said a block was getting weak in main (no main batt light ever came on)...codes got more frequent and I was using ig to reset.
on hunch I replaced the mower battery...which completely took care of codes... runs and operates fine except...abs and brake light on.. have not seen regen indicator of energy saved in display for a while.
occasionally the abs will go off but brake light on...and it will slow better dues to regn working...but not enough to get a regen indication before abs comes on again. Once abs comes on, regen no longr assists pedal.

computer shows an abs problem of something( having bad ground or locked up....and it is definately intermittent.

I can clear the code... but comes back shortly..

earier it would operate for a while and regen... but lately it will go back out on even the slightest brake if I happen to catch it and test brake.

... so summary

12 v aux when going bad with throw engine light..and codes for weak block 10 in main..via a code and require an ig reset to get dash monitor back

abs and batt indicators on equals no regen and no saved energy... and more brake pressure

question is what you think is causing the abs/ brakelight/ regen issue.

btw.. the battery build in jan appears to be doing great and my fear of it needing more attention at 6 months is unfounded

I appreciate your help.... always be quite helpful...and very accurate

 

I'm not Bob, but what I think is causing the lights is ... whatever the computer is saying it is.

You've sort of mumbled over your codes "of something( having bad ground or locked up" but those codes are the most important information you have, and these are your brakes, and mumbling over what the exact codes are won't do.

Once you go back to which exact code(s) you have, they will lead in the manual to entire, several-page step-by-step procedures narrowing down the cause until you know what to fix. That's the no-nonsense, just get it done, way to diagnose your issues, and because these are the brakes, no nonsense and just getting it done would be good.

I'm honestly a little concerned from what you've posted above (especially about taping over the sonic warning, which isn't even activated except for some of the most dangerous codes), that if you happened to get into an accident or injure someone, and an insurance company or injury lawyer happened to find this thread, they could use it to argue that you had taken too cavalier an attitude to a brake problem you knew about. So I do hope you'll dig in, use the information the computer is giving you to identify the issue(s) and proceed with a proper fix.

-Chap

 

I agree. And if you can't fix it yourself, it's no shame in taking it to a proper Prius mechanic for repairs.

 

Sorry for the 'mumbling over codes'... but I cound;t remember the codes...nor had the time in the busy schedule to find it... I have a day off tomorrow and will try to find it, and possibly pull a new one.

Having finally resolving the aux battery issue, I can now concentrate on the brake.

The brake issue has been one that has came and gone over a long period of time (approx 4-5 months) sometimes at first it was just momentarily...and later got to the point it would not go back to normal state leaving it in 'manual' brake mode...which is perfectly safe.

At first I thought it was a wheel sensor kicking out the regen...and may be a loose connector ...but the code said otherwise.
At no point have I ever thought that the brake issue was dangerous as I know well how it acts and have no problem bringing the vehicle to a stop, quickly or otherwise. I may have done differently if there seemed to be any lack of brake, but the manual system works perfectly...albeit a slight difference in not having regen(less gas mileage) and a slight increase in pedal pressure.

I replaced all the brakes myself ,,and in this model the computer is not needed to open valves with the mini vci..especially if you make sure to compress the caliper and not let it move out taking in air.

the brake job did well..and have no softness of the manual pedal,


Ok... I found the code the aux battery caused...P3020 battery block 10 becomes weak.

but I couldnt find the abs code

I found 2 codes I put in notepad on my phone....but may not be them
21420 and 22050 are the codes... but probably code to something else as I did not what those codes were for

again, I will try to pull the code again tomorrow...I am sure it will be there

 

Ok...heres the codes...and a note

C1202 Brake fluid level low...open circuit in brake fluid level warning switch circuit
C1251 Pump motor is locked / open circuit in pump motor ground
C1259 HV System regenerative malfunction

brake fluid was at minimum...cold... so added to middle of marks
also went ahead and did the air bleed utility just to make sure as it was never done on brakes replacement

ABS and Brake lights on in dash

was able to clear C1259 and C1202...but C1202 came back... suspect a dirty reservoir plug as I tried cleaning a few months ago with some spray but was old spray,...dont think it worked
The C1251 has been the main code all along. I suspect maybe a bad connector at the 'accumulator' if I am thing of correct part...as it works sometimes...most of time not... It used to be completely the other way around ...but has steadily gotten worse. The fact that it is intermittent...and work fine when working earlier... is what makes me suspect a connection as I simply cannot fathom a motor locking and unlocking so easily.

Again... manual brake part of system works, and has always worked perfectly.... absolutely no gain in pedal hardness after the bleed....so confident no air in system....pedal has always been hard and never spongy.

 

Did you do a Zero Down before checking the fluid level? It will usually be off (look too low) if you don't, and then may be too high if you added fluid (especially if pads are changed later). Edit: I was thinking later generation, don't remember if Gen 1 had a 'zero down' utility. You get the same effect in Gen 1 by having the key off, and working the brake pedal 20 or so times, until it gets suddenly hard. (Of course, if your accumulator pump hasn't been working, pedal may be hard already, and nothing to zero down.)

You should be able to pin down exactly what the issue is by following the troubleshooting tree in the repair manual (it's just three pages), along with the wiring diagram. By coincidence, this post I made a couple years ago, to explain the joys of computer-aided diagnosis, happened to use the Gen 1 brake accumulator pump as the example, so it describes exactly what you're looking at.

The wiring diagram will show you the routing of those circuits, in case it's possible there's wire damage, or a bad ground point, to rule out.

-Chap

 

Hi Chap...

No Zero down.......but as stated ...was barely at the low mark when checked...and I added just enough to bring it to almost 1/2 between marks


The diagram in the linked post is perfect ...but as you mentioned...doesn't give me the wiring routes to troubleshoot where the actual problem is. I don't have the repair manual...don't know where/how to get it unless its available somewhere online.. would be nice if I had those '3 pages' you mentioned it points to

I do , however, have the mini vci, and an old netbook it is installed on. Poor thing has a bad battery and will not run at all unless it is plugged into AC....but its XP OS does come in handy in this instance.

Already discovered that the utility allows one to exercise various solenoids, pumps, sensors...and all manner of testing setups. Well thought out by engineers of a car so aged . (when people ask me what this car is , I replay its a 'Classic' prius... THAT is a scary thought...lol )

 

One more mention...unrelated... at some point in the upcoming spring I need to find out how to add freon (procedure) as the ICE will sit and cycle more than normal due to the A/C being a tad low . I'm comparing it to the old 94 Explorer that will cycle the A/C pump when the freon gets a bit low.
I can tell by listening, and switch positions it seems to be caused by the A/C being on and cycling.


In that one, typically I can just add a can of freon maybe once a year and it runs fine.That leak is probably the notorious o-rings Ford uses...and would probably not leak if replaced... but its a 94 with 318,000 miles ...in decent shape. just don;t want to fixing a lot of stuff.
the prius A/C is a different thread...I'll have to find that when the time comes.

 

That's probably ok, but just to make sure any future readers of this thread don't get the wrong idea: the level lines on the brake fluid reservoir are meant to be checked when the system is zeroed down, and will usually not tell you what you want to know otherwise.

techinfo.toyota.com is the place for all such stuff ... all the manuals, diagrams, recalls, service campaigns, bulletins, quick tech guides, University of Toyota technician training course books, it's all there.

For 2002, paper manuals were also offered, but most seem to be out of print; if you prefer paper, you'd have to find someone selling a set. An exception is the wiring diagram manual, which is still available. But then, that's $60 for one manual, when for $15 you could spend two days with all the resources on techinfo, or for $75 you could spend a month.

The late-model wiring diagrams on techinfo are nifty: they are interactive, you can click on individual components and circuits and follow them around from page to page. I haven't checked whether that works as far back as 2002, or if that would just be an online copy of the diagram book.

-Chap

 

Thanks Chap

I will certainly take advantage of the info...
After attempting to reset...and remove the codes two days ago... the very next day I noticed that the abs light and the brake light began to stay off some. I even got to see a couple of those welcome regen symbols so I know the regen system is working like it should. There were a few times both lights stayed off for a little while but when I had to stop once a bit quickly for an early traffic light, the lights began coming back on more.

While they were off...and prior to lights coming back on, I was able to hear the regen system working on braking...and felt the added braking ability

today , when I started car, both came on and stayed on almost all day...went off maybe once or twice

I am quite confident it really acts like a bad connector that the computer is bugged about rather than something like an accumulator...and plan to find it...but will have to be on a good weather day or two when off from work as I will surely have to remove the wipers and pan to get to the area.

While there plan to install new spark plugs and due to a very small blow by, am starting to smell burnt oil like I did which replacement of the pcv fixed (quite difficult area if wiper pan not removed)...so may need to replace that yearly now.

my bet is its a simple plug pin....but once I have at it, I will update the forum of findings. Should be just a few measurements wherever that manual is pointing to.

 

Now the rest of the story.... well, at least a part of it..
I found the way to 'zero down' the brakes, did that, and checked the fluid. It was at the low mark.

Filled it to just under full.And the problem mentioned earlier went away. My Prius brakes were working perfectly.
The ABS came on maybe once or twice again , since Jan 17, but went off and did not return.
So this whole spring I enjoyed perfect brakes and the regen was working perfect as well.

Today, I pulled up a slight incline and backed out . The ABS and Brake light were on. Brakes were quite hard to press and stayed that way unlike the come and go as before.
Resetting computer with 3 ignition switch moves didnt turn off ABS.
It is now on to stay.

Got home and hooked up the TIS mini OBD and got no codes whatsoever... now THAT is a mystery!.
Went to Advance and had them read.
C1251 Pump motor is locked/open circuit
C1252 Hydro booster pump motor malfunction
C1256 Accumulator Low pressure malfunction
C1202 Brake Fluid level warning switch open circuit
C1214 Malfunction in hydraulic system


after seeing some youtube vids on ABS motors , etc , I would bet we are looking at probably a bad commutator on the ABS pump.

Havent yanked it out yet, but will in next day or two... Maybe someone has seen this before, but with it acting up before, and then going out the way it did, leads me to this suspect.

Hope someone can shed a little light on this situ. The little Electro Bug has been a great little car since I bought it a year and a half ago and did the battery reman... Battery is doing perfect.Only thing I would like to do is pull the ICE and do a timing belt replace...as I think that is what I am hearing occasionally as it Idles and suspect 230,000 miles is probably the time that should be done.