"Brake" indicator light

motogo1 motogo1 at cox.net
Thu Mar 7 11:36:29 EST 2002

There was a lot of discussion on the S4 list a while back about the brake
light staying on a while after startup. Bottom line is this. The accumulator
(bomb, same thing) is located down behind the A/C compressor. CAUTION!! do
not work on this without removing pressure from the system, you'll get
seriously hurt! Generally, they say they the bomb lasts about 7-8 years. To
test, start the car and let it idle a few minutes. Turn off, and pump the
brake. If it takes less than about 10 pumps to get totally hard at the top
of the stroke, bomb is shot. On my 91 200, it was dead when I bought the car
last year. The brakes would still work, but when you stepped on them hard,
the pedal would feel mushy and they did not work very good.
    Now, about the brake light staying on a while. With engine off, key on,
light is on=>Normal. If the car sets a few days or maybe even 24 hours, and
the brake light takes 30-45 seconds to turn off, this may also be ok. There
is some bleed-back in this system from the brake booster (normal per
Bentley) and maybe also a check valve by the accumulator. This delay is just
the hydraulic pump getting the pressure in the system built back up. My S4
does this. If it stays on this long right after shutdown and then startup,
you may have a problem, and not necessarily the bomb.  By the way, do your
brakes seem to work ok?   HTH

Gary Martin
94 UrS4
91 200 TQA .
----- Original Message -----
From: "CL Wong" <montesawong at yahoo.com>
To: "200q" <200q20v at audifans.com>
Sent: Wednesday, March 06, 2002 6:39 PM
Subject: "Brake" indicator light

> Well my brake indicator light is taking 30sec-60sec to
> turn off now.
> I've never noticed the delay before so I'm reasonably
> sure it's a new symptom. Fluid level looks ok in the
> morning, haven't checked it with a warm engine.
> With the emergency brake off and the ignition on
> (engine off) the brake light is on... is this normal?
> Not sure what to look for with the brake pumping test.
>  I've pumped the brakes with the engine off and pumped
> at least 20 times and never felt the brake pedal get
> stiff... just how stiff is the pedal supposed to get?
> Haven't checked the maintenance receipts from the
> previous owner yet and I don't recall if there was any
> brake work done in the large stack of repairs.
> Just wanted to get a quick opinion from the list
> collective... bomb, booster, other?  Not even sure
> where any of these items are.... sigh.
> thanks in advance.
> Chi
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