Re: Anti-lock brakes

[Andrew Duane USG/PE <duane@zk3.dec.com>]

> The anti-lock brake light in my '86 5000 Turbo seems to intermittently "turn 
> on."  It usually happens within about ten minutes of start-up, not all of 
> the time, and never right at start-up.  I can easily re-engage the system 
> (or turn of the Anti-lock off light off) by pressing the anti-lock button.  
> After checking a few easy things without satisfaction, I took the problem to 
> my local (Chicago) Audi dealership for a fix.  
> 
> After the dealership checked the car, their technician informed me he could 
> find no problem after several test drives, and it would cost me $120 to have 
> them put the anti-lock system on the diagnostic computer, which might or 
> might not find the problem.  I told him no thanks, and I currently deal with 
> the problem (my wife drives this car) by depressing the anti-lock button 
> whenever I notice the indicator light.  

Do you have to depress the ABS button twice, or just once? If twice,
this is a symptom that the ABS has turned itself off due to an
anomolous reading. This happened to me recently, and all (!) it
took was a new sensor. I knew which wheel it was because of some
other damage on it.

If you only press the button once, it is likely a broken button,
or something else in the button's wiring path.

Another thing to check is whether (before the light comes on) the
brakes feel like the ABS is engaging. This is a sure sign of a
broken sensor (or bad wiring to it).

First things to check is all the wiring. The sensors are on the aft
part of the inner wheel, black things the size of dimes. Make sure
all are seated firmly, the wires to them are OK, etc. I would hope
the dealer did this for you, but you know what we think of dealers....

-- 

Andrew L. Duane (JOT-7)			duane@zk3.dec.com
Digital Equipment Corporation		(603)-881-1294
110 Spit Brook Road
M/S ZKO3-3/U14
Nashua, NH    03062-2698

Only my cat shares my opinions, and she's too heavy to care.