2012 ABS Codes C1252, C1253, C1256

Sounds like the expensive accumulator

 

In a Gen 3 there's an actuator assembly and an accumulator assembly, separate items, and they're both kind of expensive and inconvenient to access for replacement. The codes, I'm sorry to say, could implicate either item; what the codes really mean is that pressurized fluid isn't holding pressure well in the accumulator, but that could be because of a sticking valve, and most of the valves are not in the accumulator assembly but in the actuator. So it's possible for the accumulator to be innocent victim in this scenario.

Considering the expense and tedium of replacing either one, any preliminary investigation to try to pin the blame more clearly on one or the other might save some frustration.

 

My 2011 198k...lit up the dash ...C1256... I hear hissing and see seepage at brake booster boot under dash. Raiding the parts off My wrecked 2010 donor to check compatibility..hissing under the dash gradually got louder and seepage is visible when pull back boot...the accumulator was cycling more and more frequently about every 10-13 seconds. I’m just going after booster/accumulator assembly code C1256 points to accumulator low pressure and I see leakage and hear hissing under dash at brake pedal where connects to assembly thru firewall.

 

The two assemblies are connected to each other, so the accumulator pump will have to run more, and you can get the same accumulator low pressure code, no matter which unit has the leak. More often it's the top one. The top one is also the one the boot is connected to under the dash.

 

Got the donor 2010 accumulator out today. The leaking accumulator cycled from 3.23V then up to barely 3.7V the decay was rapid as well... 2011 @98k accumulator kicked on at same 3.23v. Cycled to a strong 3.78v and slowly decayed to 3.23v and repeats...I’m not messing with pump at this point Toyota replaces both components.. but they always CTA for Toyota...

 

Visual inspection revealed the failure...
hissing and leakage at brake pedal under dash..

 

Leaking Actuator



Need enough fluid





don’t let run low during bleed





Did the swap.. no problem




put on all 4s




Backed up battery...


.. actuator cycles very quickly reaching upper limits and holds pressure steady about 3.5ish ...


Responds to braking...Nicely
Accumulator Pressure voltage should hold steady... very slow decay...down to 3.23 volts Then cycle... no hissing no weeping. Funny that Boot has weep holes built in ...