Thanks for this informative feed. I spent a couple days racking my head trying to figure out why my parking brakes failed after shoe replacement.
I was just about to turn the van over to the dealer when I came across this thread.
Your fix, of "threading the piston out" worked perfectly .You saved me some money and a lot of humility.

 

and about every other car in the world manufactured over the last 30 yrs with screw-in pistons for integral e-brake lol. Sometimes it actually helps to read a service manual.

 

What an eye opener this was.....I took my 2009 Grand Caravan and the brakes and rotors are all relatively new. The parking brake would go all the way to the floor and not hold the vehicle. I know the parking brake is self adjusting so I reset the cable adjusting mechanism (driver side) and nothing improved. I thought for sure it was the parking brake pedal and mechanism since it was locking but not grabbing. To replace it is a real PTA and I'm getting to old to be working on my knees....took it to the mechanic and he said I needed new rear calipers....seems the piston would contract and compress for braking but the seals were not sealing properly when the parking brake was activated thus not holding the car. Perhaps this is why my pedal was going to the floor as well though very slowly. So I too bled the brakes and there was no air in the system.

On another note....I keep my cars 7-10 years...and every time the newer ones come out with new technology....like the new Caravans 2011+ just to change the spark plugs is a real PTA. On my 2009 20 mins and I'm done. Is it necessary to have individual coil packs and eliminate ignition wires?

As for the electric parking brake and needing a scanner....manufacturers are making the cars so complicated it will put the independent garages out of business. Each car has their own little nuances in how to repair them. There will come a time when only dealers will be able to repair a car.....I remember back in the day when there were two kinds of transmission fluid. Green for Fords and red for everything else. Now we Mercon V. VI, ATF+4 SP-III, SP-IV CVT......and lets not forget the antifreeze!!!

Great information...Thanks Dennis