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Re: 90' V8 Brake light moody


    Assuming the V8 uses the same systems as the 200 series, the light may
be indicating low pressure in the hydraulic system - it goes out after the
pump pressurizes the system above the alarm setpoint. This can be an
indication you need a new pressure accumulator (AKA bomb). The bomb contains
a nitrogen charged bladder which stores upwards of 3000 psig pressure and
holds it on the brake system for brake boost if the engine is off or to
supply the insatiable boost demands of an activated ABS system. With time
the nitrogen bleeds off, the bladder collapses, and the pressure storage
ability decreases. The bombs typically last 7-8 years, so if yours is
original, it is probably toast. You can test the bomb by running the engine
until the light goes out, shutting off the engine, and repeatedly applying
the brakes. A good bomb will give you 20 or more applications before the
pedal becomes hard (indicating loss of hydraulic boost). 10 or fewer
applications and it's time for a new bomb. I had the same symptoms on my '91
200q - the light stayed on for 10-20 seconds after startup and flickered on
under hard brake application (this is a definite DANGER sign!). The bomb
test gave me one application (yikes!). A new bomb solved the brake light
situation and greatly contributed to my peace of mind.
    If the light is coming on at stop signs, your car may be DANGEROUS to
drive. You can experience sudden loss of boost under hard braking, and if
your ABS activates, your brake boost and braking ability will vanish
instantly! Check this immediately!
    Other possible causes are low hydraulic pump pressure and brake servo
problems. Thin pads show up on the autocheck warning system.


Fred Munro
'91 200q  263k km
-----Original Message-----
From: corvairss@sprynet.com <corvairss@sprynet.com>
To: quattro@coimbra.ans.net <quattro@coimbra.ans.net>
Date: Friday, December 11, 1998 1:08 PM
Subject: 90' V8 Brake light moody

>New to list and wanted to ask about the brake idiot light (not system
>check window) that is displayed on startup tends to stay on 10 seconds
>+/- after all other idiot lights go out and also comes on while brakes
>are applied sitting at stop light.  Checked fluid and all is normal.
>Is this because of thin pads or out of adjustment?
>Car stops great and doesn't pull under hard braking.
>Thanks for the help in advance.
>Steve Short
>90 V8
>(too many Corvairs to list)