ABS/DSC Issue

[AvusM5]

Hi all,

I'm experiencing an odd ABS/DSC related issue that seems to have started and gotten more pronounced over the past month. When cornering at any level of spirited aggression, DSC is intervening prematurely followed by ABS "ice mode" like behavior with a stiff brake pedal when applying the brakes following the DSC intervention. I do have a 2002 (6/02) production M3 with MK20 but never experienced DSC intervening like this when pushing the car far harder than what causes it to trigger now.

I have scanned the MK20 module and it is not throwing any fault codes. I have not data logged yet when triggering the issue. My brake lines are original at 24 years old so I will be doing those next. Could failing lines cause enough of an uneven hydraulic pressure to cause the Mk20 to erroneously trigger DSC/ABS? This definitely is not the regular "Ice mode" behavior as it didn't do this prior. There is also fresh RBF 660 in the system.

Also would it be worth replacing the brake pressure sensors and WSSs even though there are no codes present? My understanding is typically codes would be reported if there was an issue with the actual module significant enough to cause this issue.

Thanks!

-Luke

[Tbonem3]

A buddy ended up having to replace the pressure sensors under the brake fluid reservoir. I had never heard of those sensors before. Then soon after, I saw a thread here on it. Might be worth looking into.

[AvusM5]

What is really odd is that I am not experiencing a trifecta nor any fault codes.I went through the issue of the solenoids/soldering failing on theBosch 5.7 ABS unit in my M5 and having it rebuilt by Module Master. That was throwing codes and a trifecta though.

[Estoril]

How are your tires? Does this occur with DSC off?

[AvusM5]

PS4Ss with plenty of tread. Rears are brand new. I did get an alignment after replacing the RTABS and FCABs with Synchro design works monoball RTABs and Powerflex outer alloy poly FCABs. Here is the alignment sheet. Also no steering angle related codes and checked the live data to confirm that the sensor is reading accurately with the wheel centered.

[bigjae46]

I think the wheel speed sensors either give a reading or they don't and typically will throw a fault code. I'd inspect the pressure sensors, wiring harness and control unit for signs of brake fluid contamination. Could be a yaw sensor.

I'd log data which could give you a clue.