It has been so long I cannot remember: when screwing back in the rear piston on a rear disc a.b.s. equipt truck do you need to open the bleeder screw as not to damage the abs system?

It has been so long I cannot remember: when screwing back in the rear piston on a rear disc a.b.s. equipt truck do you need to open the bleeder screw as not to damage the abs system?

it is always good practice to open the bleed screw when pushing the caliper pistons back....the bore will have bad brake fluid along with metal particles....this getting into the ABS contol valves would not be good...