2013 Prius 3: two months from C1391 to brake failure

Turbogrampa · Sep 1, 2020

Eriol said: ↑

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.
Click to expand...

Turbogrampa · Sep 1, 2020

If you find this request I would like the videos as I plan on replacing my brake units soon.
I have the C1391 and the other codes as well. Just brought it home from the dealer and they want $4500
to fix it. I will be saving this post for further reference.

Tim Jones · Sep 2, 2020

Turbogrampa said: ↑

If you find this request I would like the videos as I plan on replacing my brake units soon.
I have the C1391 and the other codes as well. Just brought it home from the dealer and they want $4500
to fix it. I will be saving this post for further reference.
Click to expand...

2013 Prius 3: two months from C1391 to brake failure

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2013 Prius 3: two months from C1391 to brake failure

Turbogrampa Junior Member

Turbogrampa Junior Member

Tim Jones Senior Member