Having problems myself .. I changed all the brake pads on the car.. the rear caliper on drivers side was stiff and I couldnt get it to wind in until i took it off the car and used a vice to hold it steady.
After bleeding using the two man system i wasnt getting any pressure in the brake pedal.
I thought i duffed the seals in the master cylinder, so i clamped all the brake lines, and then i got a solid pedal so that ruled out the master cylinder being damaged.
After taking off one clamp at a time the front drivers side caliper seems to be the culprit. If i clamp the line the pedal is solid. if i take the clamp off, the caliper piston does operate but the pedal goes to the ground. after a test drive i cannot get the abs to activate because there is not enough brake pressure and pedal is on the floor.
I took the caliper off the
guide pins, pushed back the piston with nipple open, tapped the caliper with a hammer to move any settled air bubbles, bled again and still getting a soft pedal...
Really unusual behaviour.. Has any one seen this before, before i go look for a new caliper?