Yet another PMIII question.

[peeeot]

So I've been driving just shy of a month with consistent power-assisted brake response and without seeing any brake or ABS warning lights. This is good.

 

I have, however, observed that when I'm maneuvering in parking lots and on any number of other occasions, that the ABS pump will frequently operate on every pedal press. I think the most pedal presses I've ever gotten before the pump cutting on was like 3. I've also noticed that the pump will run under steady pedal pressure at stoplights; at one point I timed it and it was running every 23 seconds.

 

I've checked pretty thoroughly and haven't found any leaks in the system.

 

Every resource I've consulted indicates that this is not how the system should be operating. They suggest that these are the symptoms of a failing accumulator. The thing is, I replaced my accumulator 2 months ago with a Prior remanufactured unit. Surely it shouldn't have started to crap out already?

[LukeZ34]

I'm sure your Prior unit is fine.

Did you bleed the master cylinder after you changed the accumulator? When was the last time you bled all 4 calipers?

 

[peeeot]

Now that you mention it, no, I didn't do a thorough, full-system bleed. I followed a set of instructions I was supplied with my new brake pressure switch, which is the part I most recently installed, which also required that I remove and reinstall the accumulator. It mostly involved a lot of sharp pedal-pressing, solenoid-cycling, etc--no turning of wrenches.

 

I forgot all about bleeding. I'll give it a full bleed ASAP.

[Bossman429]

Don't forget there's a special procedure for bleeding a PM3 system:

The fronts are bled first in this system, they are bled just like a normal bleed with the ignition "OFF"; open bleeder, push pedal to floor, close bleeder, etc.

De-pressurize, and fill reservoir up.

bleed right rear: with ignition in "RUN" position: open bleeder, have a friend push the brake pedal haflway down, the pump motor will run and bleed fluid out of the bleeder. Let fluid come out for 15 seconds, and close the bleeder.

Do the same procedure for the left rear caliper.

De-pressurize and re fill reservoir.

See what the pedal feels like.