I have the brake abs trac warning lights on. With the brake accumulator leak code. Quick questions

I would tend to replace the one that I hear the noise in first and I guess you got to locate the part

 

I think I'm not alone in struggling with the names. There's an upper and lower component. The upper one:



And lower one:



I see also, while the main part description does not say "accumulator", Toyota does use the term when discussing it (per the following).

If you're replacing the lower one, there's a revised version (supposedly "fixed"), and Toyota in their wisdom didn't change the part number. Instead they rotated a label on one of the barrels, 90 degrees:


(full document attached)

 

Lower is accumulator pump assy upper is actuator . You step on pedal the actuator starts the process then the accumulator and pump fire in is what it looks like.

 

Right, that lower assembly, labeled the booster pump assembly, is also called the accumulator assembly.

When you look at it, it is two round things. One has electrical connections; it's the electric pump. The round thing next to it is the accumulator. When the pump pushes fluid into it, pressure accumulates. Once you know what it does and why it's called that, it's hard to mix it up.

The upper assembly can be called all of: the master cylinder, the booster (but not the booster pump), the actuator, and the skid ECU. It can be called all of those things because it is all of those things.

As the master cylinder, it has pistons that put pressure on the fluid when you press the pedal. As the booster, it applies extra pressure (the pressure that's already stored in the accumulator, thanks to the pump) behind those pistons, so your leg power is boosted. As the actuator, it has valves directing the resulting pressure to the four brakes as needed. And the skid ECU is there on the side of it, coordinating all that.

The pump and accumulator don't do anything special to "fire in" when you use the brakes. Their job is just to keep pressure available all the time in the accumulator, and pump it back up when it drops, just like the pump and pressure tank in a house with well water. The master cylinder, booster, and actuator just use that pressurized fluid whenever they need it.

 

Do you have less than 150K miles? If so with a 2013 you should be covered under the warranty extension ZJB since you have the code showing up. If so dealer will replace both for free.