The same thing happened to my Blazer. A common problem with these seats not working is a corroded connection from the fuse box to the three power leads for each motor under the seat. To check this, I removed the drivers side kick plate by simply lifting up on it. Next I removed the plastic panel by the hood release by fully engaging the emergency brake and pulling the panel toward the center of the car. Lift up the carpet until you find a section of wires lying on the floor. They will be close to where your right foot would be while driving. Open up the two plastic wire looms and you will find a wire junction of orange wires. When I looked at mine, the hot wire from the fuse box was completely disconnected. I cut the corroded parts of the wires out, slid two heat shrink sleeves over the wires and soldered a jumper wire inbetween them. After soldering the wires together, I slid the heat shrink sleeves over each new connection and shrunk them tight using a hair dryer. I'm sure electric tape would work, but I wanted to make sure moisture wouldn't get into the connection and cause future problems.
I hope this helps.