Dboyd

All of a sudden my abs/bas light stays on and it pops up and fault message on dash cluster amd brake pedal feels a bit on the spongy side and before i just start swapping parts as I gives up no error codes when scanned does anybody have any ideas what might be the likely culprit a fault and don't say switch in brake pedal please as it's not that. Speedometer and RPM work fine and so does cruise control.
cheers