Ok guys,

I'm really writing this post for the many who will search about the problem I had- and seeing this post will save you at least $1000.

I posted recently about my problem with my '99 540it. I described my DSC/ABS failure- but didn't really get much solid info other than some very helpful sggestions. I researched the problem and found a solution, so I'm writing to close the loop and share my experience. I'm going to paraphrase the symptoms that all lead to the same conclusions for '98/'99/'00 bmw's with DSC, and/or ASC+T. The same problems would hold for other models I'm sure.

1) the ABS, Brake, and DSC lights are all on together- maybe the CEL too.
2) pulling the code (like p0500-"vehicle speed sensor" on a autozone generic scanner) leads to a bad speed sensor conclusion. You either test the existing sensor, or r&r it, and the problem remains.
3) in many cases, the lights stay off until the car warms up. But the christmas tree always lights up eventually
4) the usual rear sensor issues can be ruled out (ie: speedo (left rear) and cruise control (right rear) both are working.)
5) Unusual brake/abs function at low speed, and other erratic glitches.

Welcome the world of silent recall. The ABS controllers manufactured in '99 by Bosch are known to be faulty. It affects alot of cars, not just bmw's. It is an engineering issue, and from a conversation with an expert on the subject which you will hear later about, it's not like you got one that was made on the monday after Octoberfest. Nope, the engineers goofed and made some wires and other gizmos too small for the amperage...

So you need a new ABS controller- but holy hell- it's a $700-900 part, and it needs to be shop coded and calibrated to your car! No DIY possible. Now it's $1000-1500. And that's if your stealer is nice, and pretty sharp at diagnostics.

{the following will contain info about the vendor that I got my ABS controller fixed by. I have no axe, affiliations, get no indirect benefit, and this is my personal opinion..........so i'm not spamming}

Enter Gavin Curtis, Module Master (http://www.modulemaster.com/)

I found this guys link on the roadfly board. He rebuilds controllers, and addresses the issues about proper circuit loading etc. He told me about how the input stages tend to fry out, and the wires oxidize due to the overload, and also due to the heat, due to the placement near the exhaust manifold. The brains of it likely are just fine. So I sent it to him, with a $318 payment, and I got it back about 10 days later.

I drove the car the whole time it was gone. On the e39, you can totally remove the ABS controller and you still have normal (albeit old skool) brakes. On a critical system like brakes, BMW designs it to function even under a complete failure of the controller. You wont have speedo either, but its better than having it sit in the shop. Best of all, since its your own controller, it doesn't have to be recalibrated. Just slap it back on when Gavin's done. I had to remove the airfilter box, but otherwise it's just 6 torx screws to get it on/off.

And it's fixed!!! No lights, nothin.

Hope this info helps you. It certainly closed the case for me. This guy Module Master is the real deal, and professional too. If I ever have another issue I'm going straight to him.

He's the Kirt Koeller of ABS!

Posted for the benefit of the board and according to law of karma by the phineas gage of auto repair.