Brake light flashing 5kcs

[John Larson]

While it's common for listers to suspect the accumulator ("bomb") when the
pressure warning light flashes, it's the last thing one should suspect if it
happens while the engine is running.  The bomb is merely a reservoir for
pressure.  If there's insufficient pressure built up by the pump, there will
be insufficient pressure in the system, and correspondingly insufficient
pressure for the bomb to accumulate.
My first suspect would be the switch on the booster.  They're cheap enough,
and I change one every few months.  They often leak, and occasionally
malfunction.  Most people don't have a way to tap in here to check the
pressure.
Wiring would be next.  Plug the wires together and the light should come on,
I think, and keeping them apart should make the light stay out.
Next suspect would be the pump itself.  A gauge is pretty important for
diagnosing this, mostly because it's pretty expensive.  Mine's marginal, but
it's been that way for 4 years so I guess I can live with the light being
slow to go out.
In my car, a 20v, the level and pressure warning circuits are separate, as I
recall (my kid has had it for 6 months, and I'm not sure).  Level warnings
can be checked by testing the switch and wiring as above.
The last thing to check would be the bomb.  If the pressure is good, and the
pedal takes 20+ pumps to get firm (engine off), then the bomb is OK.  Again,
no pressure in, no pressure accumulated.  It can't hold pressure it doesn't
have.
HTH, John