Brake Light Keeps Going On And Off! Central Locking Not Working! Help!

I am having more problems with my car which is driving me mad it seems
everyday something else breaks its really irritating I would appreciate
some advice.

Today my brake warning light came on and I stopped checked the fluid
level and it was fine and so switched my car back on and carried on
driving and the light did not come back on... whats going on there? why
would it come on and then go off?

Two weeks ago the light did the same thing, it came on and I stopped to
check the fluid level and it was too dark to see anything so I turned
the car back on and drove on till I found somewhere with lots of light
- the warning light did not come back on even though I did not touch
the fluid level - when I did stop the fluid was low and I topped it up
and I thought solved the problem so I am at a loss as to why it would
come back on?

Obviously I don't want to lose my brakes and crash! If you remember
from all my other problems with my car the ABS is not working properly
and is being fixed - I am wondering if the light coming on has anything
to do with EBD? And if so does that mean the brakes are fine just
another safety feature is not working?

--------------------------------------

Anyway, after checking the fluid and seeing it was ok I locked my car -
except the central locking would not work! it kept unlocking itself! I
checked all the doors were closed (they were) and tried again still
wouldn't work... although when I turned the engine on and used the
central locking button on the inside of the car all the locks locked
fine!? whats going on there?

In the end I had to lock my driver door by holding the key in so the
lock wouldn't pop back up when the central locking tried to unlock
itself and then lock all the other doors by opening the doors and
pushing the locks down! What is going on with my locks? with my car?
why can't it just work! It is so annoying!

I want to add the car is a 1998 Volvo S40 with 155,000 miles on it and
that I wanted to add on the way home my alarm LED was red and stayed on
- it didn't flash just stayed red - until I pressed the unlock on the
car alarm and then it went out!

I suppose maybe the alarm was activated but as the doors unlocked I
didn't notice? But then if the alarm was on surely I wouldn't be able
to drive the car?

On some Volvos the failure of the electrical portion of the ignition
switch can cause all sorts of strange gremlins. Try wiggling the key
while the symptoms are happening to see if you modulate the problem.