Jim Wilke

I have a 2000 A-8. Longtime forum members will remember it as the car I bought from list member Bart Lane just about a year aog. Thus far, it has been flawless except for the usual Audi interior buzzes and rattles. It is equipped with Porsche brakes but I doubt that has any bearing. A few weeks ago, the ABS light came on and ABS was, in fact, not working. It was on a Wednesday or Thursday and the dealership was booked up, so they told me to be very careful if I drove the car and to bring it in on Monday. I continued to drive the car and I noticed that when I started the car, the light was off but it would come on after 15-30 seconds, whether I touched the brakes or not. As I noted, ABS wasn't working. Then, after 3 or 4 days, just as I was to take the car in, the light went out and the brakes started working just fine. I've kept an eye on it for 2 weeks and everything seems to be normal.

Other notes: I store the car in a heated garage but it sits outside during the work day. Temps were in the 20s while this went on. It had been MUCH colder prior to this. This time of the year, the car is primarily driven back and forth to work, 10 minutes each way. It has about 23,000 total miles and is in near-perfect condition.

Any thoughts?

Jim

April

Hall effect sensor out of adjustment ?

Jim Wilke

Boy, I don't know. Whatever was wrong fixed itself so it must have been some kind of loose connection. What was strange was that the ABS light would be off on initial startup but then come on after 30-45 seconds whether or not I touched the brakes. I guess I'll just have to wait and see if it happens again.

April

Connectors and sensors most frequently the problem on any car with ABS.

wws03

My previous BMW had the same symptoms, and it would give me the same error. It problem ended up being a faulty brake hydrolic accumulator, like a capacitor for the hydrolic pressure. When it's bad, it take about 1/2 minute for the computer to detect the lack of pressure reserve. sometimes if the pressure is high enough, the fault doesn't come on. Well, Audi may not even have one of these things, but BMW's go bad all the time. Oh yes, my Jag has one too and it went bad with similar symptoms.

April

in VAG products since early '90s.

My car has one of those accumulators and they are a PITA. I know many Jags used them. The whole brake system runs off the accumulator pressure. If the pump fails, the system looses pressure. In most newer systems, there is a seperate pump and accumulator for the ABS system, and then a regular braking system for regular use.

AUOOOO

in my Citroen. While you are right in that they might fail when then pump fails, then I hasten to add that my 2 Cits with an aggreate of 200K miles never have had such a problem. Early models, we are talking 1950 to 1960 did have quite a number of hydraulic issues. Thousands are rolling reliably in Europe, however, it is a possible source of failure.

No real AUDI content I admit, but I love the hydraulic system on Cits, "and a BMW reference was made, and I felt that I needed to balance the inputs". (just trying to be funny if the text doesn't reflect this)

April

ABS accululators finally tear. Much depends on weather, etc. The average rate on Jags and Alfas are about 3 to 5 years before failure. Approx $230.

hisport

My A8 has a conventional vacuum booster, but past two 5 cyl Audi turbos used a hydraulic pump and accumulator ("bomb"), just as some BMW's, etc do.

Hydraulic brake servo systems don't rely on manifold vacuum to provide brake servo boost. The A8 - with its big, lazy V8 - has vacuum to spare.

John

AUOOOO

$180 for the entire set of Spheres for my Cx (6 of them!). Only goes to show that Jag & BMW know that people are willing to pay whatever to drive those cars.