[s-cars] ABS Problem

[Robert Rossato]

I don't think this is a capability our older cars have.  

Definitely possible on the newer Audis.
http://www.ross-tech.com/vag-com/cars/absbleeding.html

The notes in the above link state that bleeding the pump isn't necessary
unless you've run it dry.  Though certainly there are passageways in the
pump that aren't flushed by the normal brake bleeding.  If you really
want to bleed the ABS pump circuits, you could bleed the brakes first by
your favorite method.  Then take the car out on an appropriately safe
stretch of road and slam on the brakes hard enough to invoke ABS.  Then
flush your brakes again.  Repeat as required.  This isn't perfect as
more than likely you'll only be locking your front brakes and the rear
circuit probably won't be getting exercised.  Maybe find an empty gravel
road.  In either case, make sure you have adequate room to recover from
any unintended vehicle dynamics.

Bob

> -----Original Message-----
> From: s-car-list-bounces at audifans.com 
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of Joshua van Tol
> Sent: Friday, September 08, 2006 9:49 PM
> To: Audi S Car List
> Subject: Re: [s-cars] ABS Problem
> 
> 
> Does anyone have info on how to do this "service bleed" on a 95.5 S6  
> using VAG com? I have long surmised the existence of such a feature,  
> but don't know how to access it.
> 
> On Sep 8, 2006, at 8:55 AM, Toborg Michael (AC/ESC3) wrote:
> 
> > A code 00301 - "ABS return flow intermittent" sounds like the ABS  
> > return
> > pump fault. Either the pump motor in the hydraulic unit is 
> bad, or the
> > wiring and relay going to the pump motor is flaky. If your 
> mechanic  
> > read
> > codes, and no wheel speed fault was there, I would believe his
> > diagnosis.
> > When the hydraulic unit is replaced, a "service bleed" 
> should be done.
> > Your mechanic can use his VAG tool to cycle the valves and 
> pump motor
> > while bleeding the brake lines to get out any air in the new/used
> > hydraulic unit.
> >
> > Hope that helps,
> > Mike