Q: Low brake pedal and anti-lock brakes are not kicking in.

1995 Chevy Silverado, ¾ ton, 4x4, with antilock brakes. Low brake pedal. I have replaced the master cylinder (I did not notice any fluid in the brake booster when I changed the master) bench bled the master and bled it on the truck. Still had a low pedal. I checked the rear brakes and found both wheel cylinders leaking. I replaced rear wheel cylinders, brake shoes, and spring kit and axle seals then bled the system (including the antilock brake module, I still have a low brake pedal. Re adjusted the rear brakes and the emergency brake cable. Checked the front brakes, the calipers did not appear to move freely. I took them apart to clean and lube the hardware however I could not get the pistons to collapse so I replaced the calipers and pads. Re-bled the entire system and still have a low brake pedal and antilock brakes do not engage. The brakes will hold the weight of the truck and will (eventually) stop the truck but the antilock brakes will not kick in. The pedal engages about ½ to ¾

My car has 87265 miles.
My car has an automatic transmission.