Hi, Welcome to BMW ownership.

There will be trouble codes stored in the ABS module. To read them, you will need a good scanner with BMW software. Most scanners only read the engine computer (DME) and not all the other modules. There are many options for a BMW scanner, here are a few.

• Foxwell NT530 scanner with BMW software Foxwell NT530 BMW Software Preloaded Works with BMW Mini Rolls-Royce Latest 2018/2019 NT520 Updated
• INPA software (free) running on a windows laptop with special cables (cheap) The Z3 Diagnostics Thread: Instructions, Experiences, Discussions, Experimentation

Once you get the codes read, post them here with the descriptions and we can help you. Without the codes we are all just guessing and you'll end up installing expensive parts in the hope of fixing an unknown problem.

 

I will see if anyone local has a scanner I can use, so I can maybe save some money there.
If not, I'll pick up the Foxwell NT530 scanner.

 

Agree with NZ00Z3’s advice. You need to read the ABS module error codes to see why it is turning those dash lights on.
For less than $30 you can get the K+DCAN cable and BMW Standard Tools software on your Windows laptop. Hit the link below and follow the steps.
Once set up, run INPA, choose E46, Chassis, MK60, to connect to your ABS module. Then select F4 Errors, F1 Read errors to see the error codes.

Trust me, you’ll need this software to troubleshoot and maintain your M3.

 

$30 sounds like a much better solution than the $200 tool.
You mentioned a link with instructions in your post, but I didn't see a link. Or maybe I misunderstood?

 

You need to get your fault codes read and see where it points you. For starters, could be a bad pressure sensor or the ABS control module. My ABS module acts equally intermittently in the 3 years I've owned it.

 

The pressure sensors aren't particularly hard to replace on RHD cars luckily. For LHD, you may have enough space without removing the ABS module (but no idea). I did both my sensors while everything was still in the car.

The pressure sensors do fail. I've been in three cars with those codes, and replacing the correct sensor (or both if they're both failing) will clear it out.

 

Here are all of the codes that it displayed, and the google translation.
MSS54

• 9: no ASC2 message
• 90: 90 degrees difference of the slc suppliers too large (adjustment operation)
• 105: Plausibility check of engine temperature

MK60

• 5E20: pressure sensor 1 electrically defective

Can anyone say with certainty what these mean? Just for clarity, this is a 2005 M3 ZCP 6 speed manual.

Sorry if these are obvious. I've never had to check engine codes before. If I had to fathom a guess, these are the reasons.
The
The 4th one is DSC pressure sensor.
he 3rd one is a wheel speed sensor, and the 4th one is the steering angle sensor. No idea what the first one is...

 

A friend of mine brought over his Autel scanner... Oh boy. probably 20 codes for crazy random shit from thousands of miles before I even bought the car.

We did a full and complete reset. It looks like the ghetto tool I used before didn't actually clear anything.

Anyway, after a while, sure enough, the DSC / yellow brake light came back on. This time, after reading the codes again, it was just a singular code.

5E24... DSC pressure sensor 1

Since the last time I read it the code was 5E20, this is 3 times in a row that I've gotten a code for the DSC pressure sensor 1.

I looked at the real-time data for the pressure sensors in the ABS DSC module, and the reading between sensor 1 and 2 are way off from each other.

So just sitting idle, sensor 1 reads anywhere from -29 to -35, meanwhile sensor 2 is reading -5 to -15. This differed slightly from the first scan, where sensor 1 was +10, and sensor 2 was -0.5.

I find it very odd that either of these sensors would read negative pressure. Can anyone confirm on their car if negative pressure on either of these sensors is normal?

I also don't know if it's normal for these 2 sensors to read drastically different values, since from my understanding, they are literally the same sensor, and they are only a few inches apart from each other.

My friend wouldn't let me borrow his tool, so I didn't have a chance to swap the two sensors to see if the error followed the sensor or not. That's the next step.