Hi there,my prius v has the ABS warning lights and the scanner showed the C2152,C2152 and C2156 code

There is a special way to bleed these brakes using the Toyota scanner, Techstream, especially when its not working right. If there is no air in the system you can use the “invalid mode”. While we have a guy or two that apparently don’t like to discuss it, the brake booster assembly on these cars is known to fail. The only real solution is replacement of the parts.

 

Your most likely going to need the pump and master cylinder. OUCH..... and it has to be off a v only!

 

In the US versions a 2012 needs:
47070-12020 pump $913 mcgeorge 696 ebay used 164
47050-47110 Cylinder Assy $1405 Mcgeorge 1072
44785-02060 Gasket, Brake Booster $5 mcgeorge $3.60
00475-1BF03 Brake Fluid $22

The sequence with Techstream is RR, RL, FL, FR. Techstream guides you the step by step procedure. See the ABS ESP VDC menus for Utilities Air Bleeding.

An alternative without Techstream which is best used when there is no air in the fluid:

Invalid Mode:

1. Press parking brake
2. Power Button twice
3. Press brake petal and go into Neutral
4. Press brake x8 in 5 secs
5. Press Park
6. Press brake x8 in 5 secs and release
7. Press brake petal and go into Neutral
8. Press brake x8 in 5 secs
9. Press Park and note Blinking brake light
10. You are in invalid mode

Bleed rear brakes by holding pedal down
Bleed front brakes by pumping brakes
Power down to exit invalid mode

Consider using charger on 12v battery to ensure low battery does not disrupt bleeding

 

Parts off a Lexus CT200 also work...

 

Normally this system is brake by wire only. The brake pedal combined with other ecus just tell the brake ecu how much pressure to apply via the master cylinder. As a result it is possible to apply traction control braking without any brake pedal application. Or no braking because of regen. Or some braking combined with regen. Prius gets much of its braking from regen so you may be pressing the brake but the car is often just slowing based on electric motor regen resistance.

How it works is a long story but to give you the general idea, the pump/accumulator builds up pressure which the master cylinder/abs/brake ecu directs individually to each wheel. The pump assy has an accumulator tank that is nitrogen charged pushing a diaphragm pushing the brake fluid. That diaphragm fails and leaks nitrogen into the brake fluid. When that happens the pump runs more often and eventually fails. That nitrogen gas gets into the very complicated master cylinder assy and usually causes it to fail. The only way to completely exercise and flush every passage way is with the Toyota Techstream scanner.

If your pump is not running and its getting power you could try replacing just it and then do the full flush procedure. Initially Toyota was doing this on recall service for these failures. Then it was determined the master cylinder was often defective as well so now the recommendation is to change both. It is difficult access which means its easier to do it once than twice.

These systems fail routinely on gen3 cars. It is very important to get the right parts, many sellers don’t know a v wagon is different parts than a regular hatchback. If you have power to the pump and its not running its the critical failure. I would and did change the master cylinder also using used lower mileage parts. If you want to keep the car another 100k miles or more, I would use a new pump assy at least.

Finally the warning is saying do not try to disassemble the accumulator because it would be a waste of time and could hurt you because of the nitrogen pressure blowing parts at you. It does not mean you can’t replace the pump/accumulator assembly.

 

That is one of the failure modes that has been seen, and was subject to a recall. It was happening especially often in a run of accumulators where the 'diaphragm' (really a metal bellows) was slightly undersized, and on bumpy terrain it got banged around inside the accumulator canister, and developed cracks, leaking nitrogen gas.

Another, different, failure mode, also the subject of a recall service campaign, happens in the actuator assembly, which contains many small valves directing brake fluid. If one of those valves fails to seal completely when closed, there can be a leak of brake fluid (not nitrogen gas) back into the fluid reservoir. In that situation also, the pressure in the accumulator does not hold, this time because the fluid isn't staying there, and the pump has to cycle frequently to maintain the pressure.

The Gen 2 Prius was the one where the braking was most completely "by wire". In every other generation, the pressurized fluid does act partly through the master cylinder in concert with your foot on the pedal; there is a chamber behind the master cylinder piston where pressurized fluid enters, pushing the piston in the same direction your foot does. (When you see the Prius term "brake booster" without the word "pump" attached, it means that chamber, and not the pump.)

That really only makes a difference in cases where the electronic controls have failed (or detected a problem and recused themselves); in a Gen 1, or Gen 3+, you still have power-assisted hydraulic brakes as long as there is stored accumulator pressure to assist you (20 to 30 strokes or so). Gen 2 really did depend more on the computer seeing your braking as an input and doing the control itself, and for that reason Gen 2 had an extra box of capacitors in back just to supply reserve power to the brake electronics.

 

Some of the “chaps” around here are sometimes more confusing than useful. All Prius v and alphas at least through 2017 are gen3. Even the American left hand drives have two parts with “hoses” connecting them. The best way to know exactly which part number you need is to ask a dealer what the part number is based on the unique vin of your car.

Some of the online dealers like McGeorge will help. Chances are good it will be the same parts as I listed above. There is nothing communicating or networking on the pump/accumulator which you indicate does not run. Verify it gets no power, determine if the cost of the parts makes sense to you and go from there.