Changing Disc Brake Pads-Help

I am changing the disc pads on my Envoy. Have the discs removed on the back wheels but unable to depress the calipers. What do I need to do?

The caliper pistons?, if so you need a large c clamp and use the old brake pad as a surface against the piston for the c clamp to rest against, be careful here if you are unfamilair with brake work.

What year envoy? I've had vehicles with rear caliper pistons that needed to be threaded in. It had to do with the emergency brake mechanism built into the rear calipers. Those will usually have a hex type shape in the piston so you can insert a tool to aid in threading them.

Joel