2013 Prius 3: two months from C1391 to brake failure

Hi folks, just thought I'd share my experience here for the reference of others. I'd searched for something like this a while back, but didn't really find any relevant hits.

Just shy of two months: that's how long it took from my car throwing C1391, lighting up the dash like a Christmas tree, and taking away regenerative braking and traction control, to losing all power assist to my brakes today on the way home from work. September 9th to November 5th.

Backstory: I bought a rebuilt 2013 Prius last December with the little bit of cash I had left over after buying a house, since I couldn't take on financing right after closing. It had 124,000 miles, and I paid $5,800 for what otherwise would have been a ~$11,000 car. I think they did a good job rebuilding it overall, I haven't found any poor workmanship or shoddy parts where it was wrecked (front passenger side).

The brake system has always made some funny noises. I searched a bit, then decided it was probably normal for a Prius. Sometimes when I would brake hard it would make a louder buzzing or pumping sound, but I quickly learned to just not brake that hard.

On September 9th we pulling out of a Target parking lot, I hit the brakes to slow for a turn, and the pedal went way down before it did anything. I noticed the dash was lit up like a Christmas tree. I pulled over, read up a bit, and tested it out - I realized I still had full brake power, I just didn't have any regen, and I had to press halfway through the pedal travel to start engaging the friction brakes. It was alarming at first, but I quickly got used to it. After some reading, I decided that one of the ABS sensors was probably out, maybe the one on the corner that had gotten smacked.

Mind you this is in a city two hours away from where we live, where our daughter is staying in a really good children's hospital. We stay there 6 days out of the week. Because of that I don't get many chances to work on the car, and don't really have the cash to pay someone else to do it. Otherwise I never would have let this brake problem go on this long. I tried to get the codes pulled at Autozone, but they said their code reader couldn't pull ABS codes, and the reader they tried to sell me didn't support Toyotas.

I made a couple of attempts at checking the ABS sensors, and the front ones seemed fine. Finally on 10/15 I decided I was going to check all four with a voltmeter to confirm they all worked. After fighting with one of the rear ones for an hour, I gave up and went back to searching on this forum. I found one post mentioning that O'Reilly can pull ABS codes on the Prius, so I took my car there and found it was a C1391 - "Abnormal leak in accumulator."

I ordered the Techstream cable, and finally got that set up last week (bit of extra work getting that working in a Virtualbox VM running on Linux). I accidentally cleared the code while poking around the interface and running some tests, and hey presto, I got my regen back! It only lasted for about half an hour of driving through, before the car threw C1391 again.

I've been fiddling with techstream and reading, trying to figure out whether I needed the accumulator, actuator, or both. Lots of stuff to sift through on that!

Today on my way home from work, the (!) light came on and the car started beeping continuously and frantically. I figured it was something with the brakes so I gave them a test press, and they seemed fine at first. When I pulled over to take my exit though, it felt like I had no brakes at all. I moved the shift lever to mode, and limped home with compression braking and parking brake. Luckily this happened just a couple of miles from home, the one day a week I was in town!

Pulling into my driveway I realized the brakes aren't completely non-functional, there's just no power assist. I'm definitely not going to drive it like that though. Plugging in techstream, I've got four codes now:
C1252
C1253
C1256
C1391
Which brings us to now, with me reading up on those codes and figuring out what part(s) I need. I'm hoping to be able to order them tonight and have them by the weekend.

Sorry for the novel, but I figure some of this information might be useful to future searchers. Especially for people like I was, wondering how long they can go before getting it fixed. Get it fixed ASAP, definitely don't let it go two months!

 

Mods, you don't have to approve this thread. It's way too long, I was still on the adrenaline rush from the experience when I wrote it.

 

Still working on it. Tonight is the first chance I've had to attack the problem. Just tried to get a two day subscription to techinfo, they charged me the $20, and the confirmation email got hung up. There's no option to resend, I can't log into techinfo without the confirmation, and their support isn't available until Monday. I'm bad mad.

I'm going to sign up a second time, pay a second time, and hope they'll give me a refund for the first.

 

I did, still no confirmation email, still the same error when I try to log in: "There was an error in the page you requested. "Please contact an administrator".

I think I actually missed the confirmation email because I created an alias in Google apps for this, but Google Apps glitched and didn't create the alias the first time. This is the third time that's happened to me, from now on I'm going to send a test email to a new alias before signing up with it.

 

Thanks. The second account I created went through with no issues, I just hope they give me a refund for the first. I stepped through the troubleshooting procedure for C1252 and C1253, and got through to "replace brake booster with master cylinder". Also in the course of misinterpreting the instructions it was giving me because I'm a newb I ended up putting the brakes into invalid mode, and it won't let me run the brake bleeding utility to clear that, I'm guessing because my actuator is hosed.

I'm going to try to order a new actuator assembly tomorrow to put in next weekend. I'm hoping that will fix everything, that I don't also need the accumulator as well.

 

I heard back from the techinfo support people today. They didn't give me a refund, but they did give me a credit that I can redeem to get 2 days of techinfo again later, which is fine because I'll want it when I go to install the new actuator. If anyone has experience ordering this part new from Toyota, I'd be curious to hear which part number you used - the 47050-471x0 one, or the 04008-11x47 one. I haven't been able to find any pictures of the second, so I'm afraid to order it without making sure it's the right part.

 

Thanks! I didn't know the wheel size was the difference between those two part numbers, I might have ordered the wrong one.

I did take it to the dealer when it threw the C1391. The lady in the service department said it wasn't eligible because it has a rebuild title, but even if that hadn't been the case, the only thing it would be eligible for would be a minor hybrid controller update.

 

Replaced the actuator over the weekend. Still having problems. After I cleared the DTCs the beeping stopped for a minute, then came back. Even after doing the ABS memory reset, the linear actuator calibration, and clearing the codes again, I still have c1252, c1253, c1256, c1345, and c1451. It won't let me run the air bleeding utility, it gives the following error: "Air bleeding has failed. Please check the vehicle condition and try again. If problem persists please refer to the repair manual." I only had like an hour after I finished putting it together to play with techstream before I had to drive back to Ohio, so I haven't had a chance yet to step through all the possible troubleshooting, and apologies if I'm flubbing details because I don't have it in front of me. Any tips or advice would be appreciated, I'm hoping I don't need to go back in and also replace the accumulator.

Observations in the process: I tried to order the 04008-11347 part number. They said they weren't sure if they'd be able to let me buy that part number, the parts department guy thought the part was identical and they just gave it a different part number to track the campaign. They tried to order it from the warehouse in California that stocks it. When I went in on Saturday to pick up the part, it was a 47050-47180 from Cincinnati. Nobody there could tell me why they substituted the part, and I didn't argue because I really need to get the car going again.

Prmp945's write-up Brake Accumulator failure C1391 | Page 4 | PriusChat was super helpful. The only thing I would add is that it's a 10mm flare nut wrench, not 12mm. My total tool list would be:
10mm flare nut wrench
10 and 14mm regular wrench
10, 14mm regular socket
12mm deep well socket and elbow thing for the nuts that secure the assembly to the firewall
An assortment of extensions, needle nose pliers, channel locks, and vice grips

The brake pedal height was way shorter on the new assembly. I had to adjust the pedal height out as far as I dared, bring the sensor down as far as it would go, and then bend the bracket about 3mm to get to where the brake light would shut off with the pedal was let up.

 

Replaced the accumulator this weekend. I was able to do it without removing the crossmember or any special tools, but I am no kind of poster child for doing this job well - I left three brackets disconnected because they were very difficult to get the bolts threaded into, and I was in a tremendous hurry. I actually dropped the bolt for the inverter cable bracket somewhere around the top of the transmission, and never found it. It's gone forever now. The three bolts for the accumulator bracket were accessible with a short-ish (but not stubby) wrench though, they just took a fair bit of patience turning them a tiny fraction of a turn at a time. I'd hate to try to do this on a car that's seen twice as many northern winters as mine has though, those bolts are somewhat exposed to the elements.

I had a fair bit of trouble making all the computers happy after I got everything back together. The bleeding process kept failing. I ended up having to replace my 12v battery, it was the original one that came with the car. That helped, I was able to get further in the bleeding process, but it still failed at the stroke simulator, and wouldn't tell me why. I tried other things - the normal bleed process would get to the third or fourth accumulator zero down and fail, but I eventually got all the way through that. I tried running the linear valve offset calibration, and it would go through ok in techstream, but the lights wouldn't blink and it still had the code after completion. Tried the actuator changed bleed again, and managed to get a squirt out of the stroke simulator before it failed, so I'm pretty sure I got all the air out of the lines.

Then I ran out of time, threw the tires on, and drove it to Ohio. Even with ABS/VSC/Trac disabled, the brakes were still better than before I changed the parts. Before the pedal would go halfway down before the friction brakes would start to engage, I figured that was something to do with having regen on the first part of the stroke. Last night they engaged as soon as I started pressing down. Also no more pump sound every few seconds.

Tonight I had an hour to kill before bed, so I read more in techinfo before my 2-day subscription expired. I realized I might not have met all the conditions to make the linear valve offset calibration happy - I don't know if the steering wheel was centered, I don't know if I shut the car off within 15 seconds after techstream said to shut the car off, and I was running it with the reservoir level sensor unplugged for the bleeding process. I tried again tonight with all those details attended to, and it worked! I have a fully functional braking system with regen again!

I didn't have time to try the full bleeding process again, but I'll try that next weekend if I get a chance. Tomorrow I'm going to drive it back to Indianapolis and put the cowl and windshield wipers back on. I hope it doesn't rain.

I took a couple of quick videos during the process, not full howto jobs, just quick videos pointing things out. I can upload them if anyone is interested.

 

Also I had the car on jack stands while I was doing all this, with the front about 4 inches higher than the back because I wanted clearance to use my creeper on that end. The linear valve calibration procedure in techinfo says to run it on a level surface, so that's another reason it might have been failing.

 

Also, in retrospect, my accumulator was definitely bad. I never did a zero down before replacing the actuator, and I never got any squirting brake fluid. It wasn't storing any pressure.

I don't actually know if my actuator was bad or not, but now that I've gone to all the trouble, I'm going to leave the new one in. Hopefully now I'll be able to make it to 300k miles with nothing more serious than new bus bars on the hybrid battery.

 

That's fair. The beeping stopped when I cleared the DTCs after replacing the accumulator, and it came back with fewer DTCs, so the accumulator was my problem. Thank you for the clarification though, you're right I can't point to the accumulator just because it didn't have pressure.

 

Sure, I'll post them up this weekend. There's not a lot of detail there though, I was in a hurry. I'm not sure offhand what that could be on your car, but it's super easy to remove that plastic tray above the brake pedal. It's just two Phillips screws, push in on the tabs at the front, drop the tray, unplug the button, and pop out the wire harness going to the button. The hardest part is contorting yourself to look up there.