GM / General Motors: 1990 Buick Regal Coupe Brakes Problem [long]

Hello,

I have a problem with brakes in this great GM 1990 ABS brakes systems
Sometimes (always after night) when i push brake pedal the brake light (red)
is lighting for about 3-4 seconds.
ABS pump is works. The same thing is coming when i push the brake pedal 3 or
4 times (pumping).
Where is the problem??
Accumulator or Pressure Sensor??
Or both??
In Poland (I live here so sorry for my English) is very expensive to find
the problem.
Master Cylinder is early new from USA.
Anybody have this problem??

Greetings
Kylo
Buick Regal Coupe 3.1 V6
www.buick.republika.pl

"Kylo" wrote
 
or 

I would guess that you probably need a new
accumulator. This is the black ball type looking
thing screwed into the side of the ABS unit.
It was a common problem back in those days.

In order to properly diagnose it, you would
need some special tools to be able to monitor
the amount of time it takes the ABS motor
to bring the system up to specified pressures.
But that's normally the one item that went
belly up. Anything more.....and you are usually
looking at replacing the entire ABS unit which
is quite expensive.

Ian