c1343 Hydraulic System(RR) help requested

It is right there at the top of your FFD: Detailed Freeze DTC 571. You can look up all the details in the repair manual.

It means Hydraulic pressure control on the RR (right rear) wheel has deteriorated. Likely trouble areas are:

• Fluid leakage
• Brake actuator

Follow the inspection procedure in the repair manual to pin it down.

Complete Diagnostic for DTC C1343 | Rear Hydraulic System RR Malfunction

 

As noted in the diagnostic steps, you've checked for external brake fluid leaks and for correct adjustment of both rear brakes?

The brake ecu monitors the pressure for each wheel with pressure sensors in the actuator assembly. I assume that if one corner (RR) takes longer to reach a target pressure, or can't achieve that target (compared to LR), then it will set the code.

You might try logging data with Techstream during a few road tests. See if changes in pressures or solenoid current are any different left to right. (Scantool might not be fast enough to catch what is going on, but it can't hurt to try).

Posted via the PriusChat mobile app.

 

Yes, there should be an auto-adjust mechanism. From what you say, it sounds like someone might have assembled the brakes incorrectly. The repair manual should have disassemble/inspection/assemble instructions. Maybe compare what the manual says should be there to what you see.

 

There should be a small stamped kind of L shaped lever attached to each leading shoe with a spring, with the bar of the L resting on the teeth of the starwheel.

A subtle thing to be sure to look at is that the starwheel adjusters for the left and right sides are mirror images. The threads are different. If they are mixed up left for right, then the adjust action will actually loosen them, until they are fully turned in as you found them.

 

Here's a couple pics from the book:

Looking at things, it seems that the starwheel with the right hand thread goes on the left side and vice versa.

Posted via the PriusChat mobile app.

 

Check out the following video:

Code:

https://youtu.be/GcAcUBGTVQ8?t=1351
Start at: 22:31

How To Replace Rear Brake Shoes 1995-2010 Toyota Corolla
Jimthecarguy

.
Good Luck!

 

I'm not sure I've thought it out in that level of detail, but do make sure that whichever adjuster you're going to put on, on whichever side of the car, gets longer, not shorter, when you flick downward on the teeth where the adjust lever touches it.

 

But I would think that would be a real stretch to even think the adjusters all the way in or even mostly all the way out aren't going to affect hydraulic fluid travel once the system sees it the one time The fluid stays down there when you release the brakes the fluid doesn't all come back it just doesn't have pressure on it to keep things squeezed I would think. But I had the same code just mine was LR I changed the actuator silver and black thingy behind the inverter and all this went away I didn't even use tec stream to bleed. It was almost as easy as bleeding any regular car supposedly I may have air still in the system but the brake pedal feels better than a new one and seems to be working great.

 

Sounds like you're thinking of disk brake calipers, which really do work that way. Aside from the 0.3 mm or so that the rubber piston seal springs back, nothing actively pushes the piston back in, and the fluid just stays down there without pressure.

The drum brakes are different. The brake shoes have big return springs that really do pull them back and force the brake fluid back. The adjusters are all that stops them. If the adjusters are all the way in, the shoes will have a large journey outward, and an equally large journey back.

 

And if the drum brake wheel cylinders have to travel too far before the shoes make contact, then it can take too much time before the fluid pressure in that hydraulic circuit increases.

That makes the brake ecu sad, and then it sets codes and stops trying to apply that corner because it thinks there might be a fluid leak.

Also, the rear hydraulic brakes on the Gen2 are 100% controlled by the ecu. There is NO connection between the pedal and the rear brakes- at all. Air in the rear circuits or loose shoe fit- pedal will feel fine.

Heck, until the system goes to "fail safe" mode, nothing in the front brakes will affect pedal feel either.

Posted via the PriusChat mobile app.

 

You can sometimes notice a bigger-than-usual whooshing fluid sound as the friction brakes are applied.

It's extra noticeable if you are braking gently to a stop, using mostly regen, and then as your speed drops below 7 mph or so, you hear a sudden whoosh.

But once the ECU has become sad and stopped trying to apply that corner, no more whoosh.

 

I second that and thanks for asking as well! Now, how did time tell? Do tell!

I'm amazed the similarity with my RR value from the same code and was reported when I invested in that all the brakes were recently changed other than the ABS Actuator-Accumulator assembly. The sellers repairman thought everything was OK and safe, though to plan on the ABS Actuator assembly needing replaced eventually and there will be more warning lights and creep mode worse situation.

My FR Wheel Cylinder is 0.94, FL 0.92, RR 0.66 and RL 0.88. Same RR and code. I have 2.2 for FR & FL Target Oil Pressure and 2.0 for RL & RR.

I'm still trying to round up all the other parts and get before I start jacking her up and working on.