2010 Prius Brake, ABS, Traction Control Lights On

Dealership can check for codes, hopefully come up with some ideas, and dismiss the codes, for about $75~.

I've had similar, but also "CHECK HYBRID SYSTEM". Definite return-to-defaults brake feel. Three times. Last time around dealership noticed the OBD connector was sporadically disconnecting, suggested I leave off my scangauge see if it helps. And that did the trick in my case: no repeat in two plus years.

 

Yes.

It's possible some of the codes you can get are different—it's important to look them up in the correct year's manual (or, at the very least, the correct generation). But the procedure for reading the codes hasn't changed.

-Chap

 

Someone once uploaded this summary of 2010 diagnostic codes to PriusChat. I don't know where it came from, but does seem to match the manual pretty well, for the codes I've had any occasion to compare, anyway. You can find the C1391 on page 32.

It seem to suggest the accumulator is not holding pressure as it should. The reason could be fluid leaking out of the system (you'd have to find a wet goopy spot along the brake system somewhere), or only leaking through the system (no fluid escapes the system, so no wet goopy spots anywhere, just fluid getting past a worn internal seal somewhere and passing back into the reservoir).

If you have an external leak (fluid leaving the system), that would easily explain the level being below MIN. But you'd need to take your flashlight and mirror and go hunt for goopy spots to confirm.

If just an internal leak, the fluid should not have gone anywhere. It could be close to MIN if your pads are very worn, and perhaps even below MIN if you were checking the level without zeroing down the accumulator first. (Zeroing down is telling the system to release all the fluid stored in the accumulator back to the reservoir so you can check the level; if you don't, you'll always see a slightly too-low level, because of the fluid that has been pumped into the accumulator.)

You said your pads looked to have 2 to 3 mm remaining everywhere; I don't think I would expect the fluid level to get quite down to MIN until they are more worn than that (1 mm is the wear limit, IIRC). Did you zero down before checking the level?

-Chap

 

It's an actual thing you do, so the way you know it's been done is because you did it.

If you have access to a laptop with Techstream and a J2534 cable, you just go into Techstream, in the brake utilities, and tell it to zero down. You hear a PFFFSSSSSHHHhhhhhhhhhhhhh.... and when it's all done, that's when you check your fluid level. That's the easy way, if you have the stuff.

If you don't have Techstream, you can zero down a Gen 3 by turning the car off, removing the ABS pump relays, then pushing the brake pedal a few dozen times; you know you're done when it suddenly goes from fairly easy to push to pretty much rock hard. Then you go check your fluid level.

The same approach works in a Gen 1, in case you ever need to know that. In fact, the Gen 1 pump can't run if the key is off, so you don't even need to pull the relays for that generation. (For any Gen 2 owners reading this, your generation is the oddball; check your own repair manual, because you've got a different hydraulic system that doesn't lend itself to this procedure.)

I respect that; 1 mm is Toyota's specified wear limit, you won't get in trouble for preferring to change sooner.

That description makes me wonder if one of the SLR__ valves in the actuator is leaking slightly. Car is opening the SLA__ valve until the target line pressure is reached, closing the valve and expecting the pressure to hold, but it's bleeding off through the leaky SLR__ (whence it returns to the reservoir; this would not be an external leak), until the computer notices and jiggles SLA again to keep the pressure at the target, repeatedly.

If you have Techstream, there are some "active tests" you can run, opening and closing solenoids individually and watching what the pressures do.

-Chap

 

i have the same issue exactly, dealer wants me to replace the whole ecu of abs traction control and skid control for over $4000. my car is at the dealer now, abs not working and i think it takes longer for the battery to charge, so maybe it affects the regenerative system, i dont know what to do.

 

car is still there at the dealership, i refused to take it, although no charges, they totlly messed it, no regenerative, no abs, no skid control, all those symptoms related to same ecu. two more codes popped c1345 c1451 in addition to the b1585
@ChapmanF gave some good info at his post thats came from the techinfo accountin regards to code c1451 ( thanks ), i will take a note and see if dealer want to bleed the brake system,

 

Do you have the exact same set of trouble codes as the originator of this thread?

If not, it is more helpful to start a new thread than to do a "same issue exactly" hijack of somebody else's.

-Chap

 

This exact thing has happened to my 2010 prius. It started when I slid a small bit in some snow on my street. Abs, brake, and anti lock brake lights on. Regenerative breaking not active. They have intermittently turned off and the regenerative braking resumes normal function. Currently, it's been stuck in the lit position for over a day. The original issue started about 4 days ago. Did we come to any conclusions ?

 

Do you have the exact same set of trouble codes as the originator of this thread?

If not, it is more helpful to start a new thread than to do a "same issue exactly" hijack of somebody else's.

-Chap

 

Wow. Sorry. First time posting on this website. I was just looking for some ideas and recommendations.

 

Welcome, then. The recommendations are easy: the warning lights on the dash only tell you there is a problem, not what the problem is. The hundred or so possibilities for that are identified by the trouble codes you read from the car's computer when the warning lights alert you to do so. So that's the first step.

A lot of the car's computers can only be read by a computer with Techstream software and a J2534 cable, but conveniently, the brake codes can be read out (in abridged form) just by using a short jumper wire and counting some light blinks. The details for doing that are in several other threads, some just updated today, in fact. You'll end up with one or more two-digit codes, and once you have those, we can start to get somewhere with diagnosis.

In general, if you've read your codes, and you find an existing thread where somebody had the same symptoms and the matching set of trouble codes, it's a safe guess that you might have the same issue involved in that thread, and it might be worth tagging on.

On the other hand, if you haven't read the codes yet, and all you know is you have some issue with brake lights on your dash, and you tag onto somebody else's thread because they had some issue with brake lights on the dash, there's very little reason to think your issue is the same one the thread's about, and future readers looking for information in the thread will be put at a disadvantage. So in that case, it is better to start a new thread that will be specifically about your issue.

Of course, even when you start a new thread, if you don't include your trouble codes in the first post, we sort of know what one of the first suggestions is going to be.

-Chap

 

In gen 3, the master cylinder is one unit (also incorporating the abs actuator and the ecu) and the accumulator is a separate unit, so if you can stand to do enough diagnosis to distinguish which one is at fault, you might save some r&r. Or you could just swap one, then the other if the first didn't do it.

The master cylinder/actuator is more expensive, but the accumulator is the one with real accessibility challenges in trying to replace it....

-Chap