I found that i had to top the brake fluid too often. workshop looked for leaks, none found. determined that it needed new master cylinder. (it was full of fluid). They bought new unit from dealer. can only bleed two brakes (diagonally) other two show no pressure…is there some kind of switch they have to operate (VSC system related??)
Nope, no switch. Sounds like the “new” master cylinder isn’t working. The new master is likely a remanufactured unit.
“Workshop”?? Standard procedure is to bench-bleed the new master before it’s ever put on the car…That way, no problems…