ABS 'bugs' was Re: Augered in my 5000s wagon!

[Stulen James <JSTULEN@dcm.dofasco.ca>]

|A colleague came into the office one day and claimed that his ABS system 
had
|locked up completely (Ford Granada 2.0EFi).  I tried it on a thoroughly 
iced
|car park for half an hour, and succeeded in getting my Granada's wheels to
|lock
|twice.  If you catch all wheels simultaneously, the system has no input to
|tell
|it the car's still moving - you can slide along at 20mph, and the ABS 
system
|thinks you're stationary. I wonder if that's what the acceleration 
detection
|switch fitted to ur-quattros from April 1988 is for.
|
|ABS will, of course, almost always LENGTHEN your braking distance.  Does
|anyone
|here ever switch it off - and if so, why?
|
|On another subject - someone just promised me a complete set of service
|documentation in German on microfiche.  Fingers crossed!
|
|Phil Payne
|Sievers Consulting UK
|Vice Chair, UK Computer Measurement Group
|+44 385 302803 Fido 2:2503/415  CIS 100012,1660

Aw, ABS 'bug' stories, this is one of my favorite topics of discussion.

I heard that in GM cars with ABS if you were to 'lose the car, due to 
oversteer' in a high speed corner, that is exit the corner backwards at high 
speed (when you should be going forwards), you can stand on the brakes but 
the ABS will intervene and will NOT apply the brakes at all because it is 
confused by the massive change in velocity (direction and speed) of the 
wheels on the car.  I heard that the Bosch ABS system on  Porsche's  had the 
same bug until a test driver took an Engineer out on the track and 
deliberately 'lost' the car in to corner to demonstrate how the brakes will 
not apply once the car has spun around.
The is all hearsay, of course.  A slightly more realistic story happened to 
a friend of mine in his Eddie Bauer Blazer (or whoever makes those things). 
 I was not in the truck at the time, but he swears this happened and he even 
repeated it.  In a parking lot he happen to be driving with the right side 
of the truck on glare ice and the left side of the truck on bare pavement. 
 He says he applied the brakes and the pedal was 'wooden', no matter how 
hard he pushed he got not brakes whatsoever.  The scared him greatly, as it 
was only luck that no one was crossing the intersection he went through.  He 
went back and tried it the otherway, left on ice , right on pavement and the 
ABS operated just fine.  He repeated the first event again and again got a 
'wooden' pedal and no decelleration.  He says he talked to another guy who 
has a Blazer, and who experienced the same thing once.

Anyone else heard of events like these?

Interesting stuff, what?
James