A8LDriver

Hello Everyone,
I started my car yesterday and lo and behold my ABS light popped on, it beeped, and the BRAKE light is blinking. I have read quite a few threads saying that I could have a short in the front driver or passenger side ABS sensor wires. I pulled both connectors and there are 4 male pins. I checked them horizontally and got about 0.2 kohms on top and 1.5 kohms on the bottom two. They both read roughly the same so it makes me think they are okay. I don't have a VAG COM because I can't afford it yet but I was wondering if you guys had any input. Also I live near Minneapolis, MN and if there is anyone with a VAG COM that would rent or borrow it to me it would be much appreciated. I appreciate all of your help.

Regards,

silverd2

I'd check all 4 sensors, mainly for cleanliness and check all 4 rotor pick ups through the sensor holes. Clean all with brake cleaner (or similar) is necessary.

What year model? ESP?

Perpetual Novice

The other possibility is the ABS control computer needs to be rebuilt. the ABS computer often suffers from loose traces, and when it fails you get the ABS light on and blinking brake light.

I've been told that modulemasters.com does a good job rebuilding them, I haven't tried it yet though.

A8LDriver

The model is a 2000 A8L. I was going to pull the sensors and clean them however it seems that when they are dirty it is more of an intermittent issue and typically at low speed. I get the issue right when I turn the car on. I had heard that Modulemasters was a good at rebuilding the ABS units however I guess I would like to know if that is the problem. I heard the VAG COM unit could tell you what was wrong. Should I just get the error code read or buy a VAG COM reader, very expensive!, or what do you recommend? I appreciate all the help everyone.

Regards,

Perpetual Novice

there used to be a vag-com locator tool, but I don't know if it still exists. Post your location in the vag-com forum and ask if anyone can help you for a beer. Good luck!

silverd2

Terminology (according to Audi/Bentley manual): ABS Control module (computer) is inside the car under the dash (left) and rarely fails.

The ABS hydraulic unit under the hood has an electrical control box connected to it...this is the unit that modulemaster can repair. Audi dealers usually replace the entire hydraulic unit (huge $$$!), which is rarely necessary. There have been lots of failures in the electrical "module" connected to the hydraulic unit, but not that common on A8's...it could happen, though.

In a 2000 A8L you should have ESP (electronic stability program) which depends on the ABS hydraulic unit to operate. If there is a problem in the hydraulic unit, the ESP is disabled and that warning will come on (circle around a triangle), the same symbol that lights when you deactivate ESP with the switch on the dash. With ABS hydraulic unit failure you might get other lights too, but definitely would have an ESP light on.

If no ESP light the fault is likely outside the hydraulic unit...in which case starting with basics, like sensors, is a logical path...plus fluid level etc.

VagCom would tell you where the fault is and often can test and correct functions in the ABS. A well equipped independent mechanic will have VagCom (oe equivalent)...since it reads any car, any brand sold in the US since 1995.

Auto parts stores (Auto Zone, etc.) can read codes with a regular pocket code scanner...usually for free.

Are you getting an ESP light?
Have you tested the brakes on a slick surface lately?

silverd2

P.S. Modulemaster has an online guide for trouble shooting.

Check out their diagnostic wizard:

http://www.modulemaster.com/en/wizard/index.php

Perpetual Novice

More info from the D2 archives. the fault code 01203 is the key here I think (its what I have as well)
https://www.audiworld.com/forums/sho...&highlight=ABS.

silverd2

Do you get the ESP light as well? ...if your model is so equipped.

Perpetual Novice

My car doesn't have ESP.