[douglee25]

Originally Posted by patroklai

Thanks for the update. The long, mushy pedal is unfortunately either a sign of air trapped somewhere that is unwilling to get released or a failed valve at the pump body. I think replacing the pump makes sense. You can start by replacing the mechanical part of the pump and repeat your bleeding steps. If this does not help, then it is possible the electronic side of the pump has failed (this is the actual DSC module with the selenoids that actuate the valves). If this portion has failed, it can be replaced but needs to be coded to the car.

In my case, I swapped out the valve side and not the selenoid side. I did so much back then I don't know what actually did it. But I was exactly in your position a few years back and eventually hit a bit of luck to get through it.

I now dread doing Blake fluid flushes on this car. 😂

Funny thing is, the pedal is hard. The only thing is that with constant pressure, the pedal still creeps down about 1 inch and stops.

I wish someone knew this answer, but I believe when you run the DSC calibration test, the master cylinder isn't even in the equation. It's everything down stream from the ABS unit. If that's the case, the master cylinder has nothing to do with a potential issue now. It's the ABS pump unit, the lines, or the calipers themselves.

One other thing I forgot to mention is, I also removed every caliper and checked behind the brake pad on the piston side to make sure the piston boot wasn't leaking. They were all 100% dry.

[douglee25]

New ABS pump and module ordered from a 2011 unit with 90k miles. $230 shipped.

Literally found this post which has the exact same issues we had. He replaced the pump and it fixed it.

https://z4-forum.com/forum/viewtopic.php?t=135378

[douglee25]

FYI -

Applied brake pedal pressure while in Ista and monitored all four corner pressures.... They read identical. Holding constant pressure on the pedal and the readings don't fluctuate. That tells me there's no hydraulic leak in the system. It's gotta be the DSC/ABS module.

Will know more hopefully by this weekend.

[patroklai]

Sounds good and I agree. The pump pump side of the abs unit likely has a problem with a stuck, loose or slow valve.

Once you get it, swap out the electronics and reinstall. Remember to bleed at the ports to minimize the amount of air that could get trapped further down stream.

Keep us posted.

[wjc4195]

Originally Posted by cjdzombie

I'm having trouble finding a working download link. Can someone message me a link?

Did you get it, could you share?

[patroklai]

Originally Posted by douglee25

FYI -

Applied brake pedal pressure while in Ista and monitored all four corner pressures.... They read identical. Holding constant pressure on the pedal and the readings don't fluctuate. That tells me there's no hydraulic leak in the system. It's gotta be the DSC/ABS module.

Will know more hopefully by this weekend.

I just thought of this, and surely something you already know but the car has to be on the ground with the steering wheel centered to run the dsc calibration.


Sorry if I'm stating the obvious.

[douglee25]

Originally Posted by patroklai

I just thought of this, and surely something you already know but the car has to be on the ground with the steering wheel centered to run the dsc calibration.


Sorry if I'm stating the obvious.

Yeah, I've tried it on jack stands and on the ground with tires. Same result.

[douglee25]

Posting the same response here as my personal thread in case it helps someone.

Well Gents... It's fixed!!

Unbelievable but it was the DSC/ABS block all along. I've never seen anything like that myself... No way to check it that I'm aware of. It took a whopping 30 mins to install the new (old) unit and about 10 mins to bleed the brakes. The pedal felt solid even before bleeding. Ran the steering angle calibration and then the DSC Calibration test... Both passed immediately... No codes. ABS works on the road. Beautiful sight. Only took me a month or more between kid's sports and life.

Thanks everyone for the help.

[patroklai]

Nice victory. Hope this helps others that are on similar quests.

Pat

[douglee25]

Agreed!