So as I alluded to yesterday, I thought I had finally found the last knob I’ve been looking for. This knob is the brake pressure control for the electronically distributed ABS system in the E2XX.
In the good old days, used to be I could set things up with proportioning valves and a bias controller. Easy-peasy throttle-squeezy. Even with ABS systems, because ABS R DUM. (Oh dear. Post is about to get educational. You’ve been warned.)
See, all the way back to the Teves and Kelsey-Hayes ABS systems of nightmare, ABS was actually not that terrible to work on. This was because ABS operated on the concept of ‘channels.’ You had single-channel, 2 channel, up to 4 channel ABS. Single meant you had one ABS sensor set and the pump was only connected to either the front or rear brakes. 2 channel could be either independent wheels or independent axles (most commonly it was implemented as axles, giving you “four-wheel ABS!!”) The most advanced you could get was a 4 channel system which would allow you to control each wheel individually.
In all of these systems - and also current systems - brake lock conditions are detected primarily through the Wheel Speed Sensor. The computer infers that the brake has locked up or is locking up when the delta between speeds on an axle exceeds a certain pre-programmed value. (Note the ‘primarily’ qualifier. I’ll get to that.) This is all well and good when your primary concern is keeping idiots from killing themselves in snow. Unfortunately, telling them they have ABS negates all the benefits because people are stupid.
Now as to the plumbing, the reason ABS systems still worked with a proportioner and bias controller is because the brake system was still designed with ABS as optional. So you have a standard brake master cylinder (2 or 4) which feeds already proportioned output to the ABS pump, which then modulates delivered pressure. And that’s all the ABS pump did. When you lock up, it modulates pressure to the caliper or drum. (This is also why ABS works on disc and drum.)
Of course these systems are a COMPLETE shitshow because ABS is not an OBD-II covered item. That means GM uses C codes (and a separate EBC interface not accessible via OBD-II,) Chrysler uses “whatever the fuck we felt like that week,” Ford uses U codes, and so on. But as long as you don’t need to work on the pump you can generally ignore that.
Modern ABS systems were designed by some asshole who said “you know what it would be great if we made it COMPLETELY impossible to work on? BRAKES!” And when I say completely impossible, I absolutely do mean that.
First of all, the power is from an electric vacuum pump connected exclusively to the reservoir assembly. So already our drive-by-wire shitshow is off to a phenomenally pointless overcomplication. And let me tell you, that motherfucking pump, there is NOTHING you can do with it. $130 of “get fucked, slim.”
Ah well, at least that’s the worst of it, right? WRONG. THIS IS:
Those two openings on the top are the reservoir attachment. That plastic plug on the side? Unbiased output. Goes to the actuator. It is called an actuator because it is the only thing that ACTUALLY ACTUATES your brakes. This:
Two balanced pipes, four imbalanced pipes leave, with those electrical connections telling you to go fuck yourself if you think you’re going to adjust your brake bias.
It’s all computer controlled, by that computer right there. If you want to adjust your bias and sensitivity, you can’t do it post-pump. Because it will detect the out-of-spec and consider it a brake failure. And you really think they’re going to tell you how to manipulate this system? It’s a safety system. They don’t like lawsuits. And if you tamper post-output? It knows, it codes.
So I thought, because I’m really quite shit at taking these things apart and deconstructing code I don’t have access to, that maybe I had finally found the knob. The E2XX nose-dives very badly. I dislike this. I wished to deliver more bias to the rear brakes to correct this.
That silver pile of hate above is the reason I cannot. I have to tell it to analyze all the brake pressure values, wheel speeds, and DELIVER MORE TO THE REAR YOU SPITE-FILLED WHORE. But everything I found was expressed in individual channel, without telling me WHICH channel. EBCMs are notoriously difficult to even attempt to reprogram.
I managed to identify some of the information I’m still lacking, but I did not achieve what I had hoped. And I’m starting to believe that I may not be able to, because next I run into the traction aids. Hey guess what? ESC/TSC is performed by braking for you.
And this pisses me off so much. I’m so close to solving nose dive with stock parts. Because, yup!
Electronic shocks. Varispring or whatever. Who gives a shit. I found that knob pretty quick. But addressing brake dive with suspension is wrong. Reduce dive with brakes. Adjust rebound to deal with it, life’s grand. Except when it isn’t. Like right now.
I don’t think I’m going to solve this puzzle before mine has to go back. I’m seriously considering finding a ‘15 Regal GS 6spd to continue the work - they depreciated 50%+. But I’ve got other cars on my plate. Other cars I’d much rather own and wrench on.
I think this one is going to be the one that finally declares victory. Just not enough time left, and I’m too frustrated. It’s taken me too long to get here, and I’m still failing, because I’m blindly fumbling around in someone else’s code without a map.
That is because of an incalcuable level of bullshit at work, including our EVP of Engineering saying, direct quote, “we need to improve our talent” and “You need to help me and HR onboard my people faster” in an all-hands meeting. Bet you’ll never see someone pull that in front of the people he was referring to ever before or since. Spent his whole presentation saying that we were idiots, incompetent, and worthless and were only here until he had enough of his flunkies on the inside to get rid of us. (And these people are truly incompetent. One of them will read one paragraph of a manual and argue with me, refusing to accept the facts 3 paragraphs in, or the facts when it’s attempted.)
So hey. If any of you are hiring a very senior level IT person in the OS Engineering / SRE / Not-Buzzword-Bullshit DevOps space... I’m looking.