Brake Pedal Sticky and Slow

Youtube is your best friend.

Here you go C1231 Linear Valve offset ECB (stiff break pedal)

 

Does that video even have anything to do with C1231? Its title says C1203 and C1345, and those seem to be the codes that show up on the scanner in the video itself. C1345 is the familiar please-do-solenoid-offset-init code.

JohnStef has reported C1231, steering angle sensor circuit malfunction.

 

Calm down just trying to help the guy.

Not so much that video itself but the page of that link shows other videos pertaining to this issue. Apparently from what i gather is linear offset affects brake stiffness.

May even be the skid ecu as he had VSC.

I feel for the guy this is what scared me about the actuator failing and going down the sick Prius rabbit hole.

.

 

Do you remember if you saw any there pertaining to C1231? It might save time to link to those.

One inconvenience of the [media=youtube]yadayada[/media] style of link is it just gives you a media embed and doesn't directly show the video's info or comments or other suggestions. Sure, somebody can take the extra step of clicking "watch on YouTube" on the embed (or just change the embed/ to watch?v= in the URL) but it's kind of an extra step.

I did that, and then did a Find In Page for C1231 to see if it was in any of the comments or suggestions, but I struck out.

 

Gentlemen, thank you for these leads.
When Ed suggested going further into the library of videos that made more sense, thank you Ed. I watched a couple of related videos hoping for discussion of a variety of symptoms - no joy.

I would like to contact the guy at Toyota Maintenance and see if he has any insight on this - but I don't know how to get a message to him?

 

I tried a test this morning with a helper. I wanted to isolate the right wheel/left wheel rotation to see which one has the delayed brake release. Starting with the passenger side I jacked this wheel up free from the ground, turned the car on and put it in neutral. My helper pressed the brake down normally to keep the car stationary, I applied rotation by hand to the wheel in the braked condition and called out "up" to my helper. I noted the delay, it was over a second. This is the symptom I want to isolate. This was repeated on the driver side and it was noticeably less, maybe a 1/3 of a second. But when when this was repeated on the passenger side to prove my results, it was a much shorter interval. Nothing conclusive.

I will try this again later in the hot part of the day after driving a bit to get the car fully heated up.

 

2nd test as described above, one wheel free, trans in neutral. Alternated the test twice on both sides, both wheels had the two second release delay.

I am going to rule out sticky caliper and collapsed brake line.

Now I am very interested in either the stroke simulator or the master cylinder.
I am also interested in doing a complete brake bleed, all 4 wheels.

 

Happily the VSC is gone, my radio and dash clock were dead, this happened a couple weeks ago. I didn't care about the radio so this was ignored. Last night after a fuse was replaced the radio works, the dash clock came back on, my combi meter now behaves properly, the warning chime that the key fob is still in the slot now works - and the VSC light is gone! It was a 15 amp fuse in the engine compartment, I think it was DOME on the diagram.

No change to the delayed brake release

 

Update
My brake pedal brake brake light switch was not adjusted correctly, it was too close and cruise control disengagement took a pretty stiff brake pedal tap, I thought, maybe this could be a cause of delayed brake release. Corrected this and no change to the delayed brake release but the cruse disengagement is now just right.
My brake pedal stroke sensor was out of calibration, 1.08 low side 3.45 high side, the correct values are .8 low side 4.17 high side at rest position. After some serious sweat and contortions I proved this was not the problem.
My symptoms are definitely heat related, 1st thing in the morning when the car is cool (55F to 75F) there is no brake pedal delayed release. At the high heat part of the day, having driven 20 minutes or more on hot pavement and releasing the brake at a green light it takes 1.5 to 2 sec for the brakes to release.

I am replacing the master cylinder today. The brake system will get all 4 wheels bled, my bleed method is, car off, depress the brake with firm resistance and one by one, furthest to nearest bleed out the wheel cylinders. 3 oz per rear line should be enough, half for the front, total of 9 ot 10 oz brake fluid minimum. The Prius sends a stead low velocity flow - very easy.

 

Keep in mind that, while replacing the master cylinder, you are likely to allow air into the actuator.

There are numerous valves and passages in the actuator, and the ECU-controlled long-form brake bleed procedure will operate all those valves in special sequences to chase the air out of all of those passages. No other procedure that you might think of improvising will do that.

 

Salvage yard master cylinder installed, brake pedal blead all 4 wheels, brakes work perfect. Very happy. No dash lights.

The brake action is much improved, I had gotten used to bad brakes. It takes much less pedal pressure to operate the brakes. But I must see this improvement hold up on a 95F sunny day, it only got up to 85F today.

 

ChapmanF and edthefox5 thank you both for your insights and help.

 

Did you keep the old M/C?

How does that one feel, just stroking the plunger in and out?

 

I still have this, it is stiff and kind of sticky when the rod is pushed.

 

Sometimes the easiest explanation turns out to be the right one!

 

Follow up to the resolution of the brake issues. The brakes are working fine and my MPG is up 5% to 10%. I don't know if this is correlated but it makes sense if it is.