No, this isn't about my abdominal exercise program, it's about my anti-lock braking system! Since I've owned the car, the ABS warning light has been on, as well as the traction control light (which is controlled by the ABS system, applying single brakes as needed for traction control). Amazingly, in Pennsylvania you don't have to have working ABS to get a safety inspection sticker. You have to have working fog lights if fitted, and a working windshield washer if fitted, but your ABS brakes can be AWOL, no problem!
But, I want them to work. Checking the codes with a code scanner (first at Jack Miller's shop, and later with one I bought from Bavarian Technic) gave multiple codes, pointing to the pump motor and the ABS control module attached to the motor. The parts are still available new from BMW but are hideously expensive (just pennies under $2,000), so I was pleased to find a used module and motor for $220.
Of course, with used parts, you never know the condition, and if that ain't foreshadowing, I don't know what is! But for now... let me document the results of some research for Internet browsers who might wind up here - there's a lot to consider.
First, know that there are a lot of running changes in the ABS system for Z3's. So many, that the Bavarian Technic scanner can't auto-detect what I have exactly. I called them to ask what I had, and they said, "Just try checking all of them. You'll get some phantom errors, but your real error should be there too." Not incredibly helpful. The take-away is to make sure you search for the exact series of controller and pump that you have, ESPECIALLY if your Z3 is a 1999 model like mine.
You see, in 1999 BMW made a one-year cost-reducing design change in the Z3 (not M Coupe) - they removed the ABS relays, and had the main computer module control the ABS module directly. I'll bet that's why my system is toast - relays help handle high currents, and running them directly into the controller instead might have decreased the life of the unit.
The first thing that hinted this possibility to me was finding instructions to activate the ABS pump by pulling the relay, and installing a wire jumper in the plug from pin 30 to 87. That sounds daunting, until you realize there are only five pins - no idea why they are numbered that way. I looked and didn't find the relay, so then I checked the Bentley manual, and the wiring diagram for 1999 was missing - it skipped from 1998 to 2000. Wow, that's annoying - that manual cost 90 bucks. I later found Internet confirmation that 1999 was special.
Anyway, for those in the same boat, at press time at least, this link downloads the entire 357-page wiring diagram for a 1999 Z3. You're welcome.
Another thing to know is that when you change the ABS pump, you need to activate it during brake bleeding in order to get all the air bubbles out of the pump. The dealership uses a special computer to do it. I had expected the Bav Technic scanner to do that also, but it won't. Specifically, it will do it for other BMWs but not for mine, with its special setup. Swell.
Searching the web for other techniques to accomplish this gave these five general opinions:
1. I didnt' do anything special to bleed the controller, and it was fine.
2. I didn't do anything special to bleed the controller, and the brakes were terrible, all the time.
3. I bled the brakes, then took the car out and made several panic stops to activate the controller, and then bled the brakes again. Repeat several times, maybe.
4. I bled the brakes, then had an assistant in the car with the engine running, pressing the brake while I opened each bleeder in turn. This causes an ABS fault that triggers the motor. You have to turn off and restart the engine each time before opening a bleeder.
5. I "drive" the car while still on jack stands, and jam on the brakes to trigger the ABS. Bleed all four brakes again. Trigger and bleed, trigger and bleed.
Since my lift is really quite stable, I'm considering using option 5. More soon!
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