wife's 2008 mazda 5. problem started a few weeks ago, brake became very soft, you have to press pretty far down for the brake to work. Took it to mech #1 (I usually go to him but he has less diagnostic tools) he couldn't find any leaks or what the cause. I had him did a bleed anyway but problem still exist. Went to mech #2 today, he told me it's the abs module and master cylinder. I asked him how did he know those are the problem even although no abs light, he said he has done many of these and it's usually the internals of the abs and the hydrualics.

If I want to do the job myself and get a used oem on ebay, does the job require any re-programming or pretty much just plug and play? anything to watch out for? Thanks.

 

Just bought a 2013 with 106k km. Previous owner had soft pedal, mech said master cylinder, which didn't fix. Next on the list was the ABS module, which solved the issue. Car was never abused, kept in a dry underground parking lot. Cost, all in, was around $2k Cdn.
I have read that the valve/module can be 'bled' by driving and activating the ABS with brakes, but no experience with this myself.
I have some info for the 2010 and up but nothing for the previous models. The service manual says to follow the installation instructions that come with the new part, not all that helpful, eh?

 

had mech #2 replaced the master cylinder, problem went away, hopefully it wont come back.