Sometimes it helps to know what makes the brake failure light come on, and, also, what can allow the brake pedal to move with little braking occurring.

The 240's without ABS have a dual circuit system. One circuit connects one part of the MC to one piston/cylinder on each front wheel, and one of the rear wheels. The other circuit is similar, a cylinder/piston in each front wheel and the other rear wheel.

If you look at the MC, you will see two "output" lines going down to a connecting block mounted on a frame piece. Two lines into it, six lines out of it, and an electrical connection.

That octopus block contains a sliding piston that moves only if the pressure in one circuit is not balanced by the pressure in the other circuit. If it moves, the movement closes the ground side of the brake failure lamp lights.

The piston moves if there is a leak in one circuit, and there can be other reasons, too. Note that the grounding is what makes the light come on, so a ground occurring elsewhere could make your flickering light.

The MC has two separate pistons, and the fluid reservoir is divided, too. If one part is low and the other not, there's a leak. Be sure that your MC is full on both tanks.

If a piston seal is worn, light pressure on the pedal can let the fluid flow past the piston - pedal moves and no braking. Heavier pressure seems to cause the seal to flare out and make a tighter seal, and braking can then occur.

I have tested the MC while waiting for a green traffic light on level roadway. Car in Drive, let off the brake to let the car roll slowly, then lightly apply the brakes, does the pedal "sink"? If yes, step harder on the pedal, brakes hold OK? MC needs replacement or repair (same labor, similar cost). Get a Volvo part.

Good luck with your diagnosis and repair.

Bob

:>)