Are you sure you've got the factory Echo power and ground wires hooked up correctly to the Pioneer loom?
Have a read of this thread for the factory Echo wiring colours:
http://www.toyotanation.com/forum/t322762.html
The wiring colours for most Pioneer head-unit looms is like this:
Red----------------12v ignition (switched)
Orange-------------12v Memory (bat. constant)
Blue----------------Power/Antenna Control
Black---------------Ground
Green---------------Left Front Speaker +
Green/Red-----------Left Rear Speaker +
Green/Black---------Left Front and Rear Speaker -
Gray----------------Right Front Speaker +
Gray/Red------------Right Rear Speaker +
Gray/Black----------Right Front and Rear Speaker -
If it still doesn't work, then check that the fuse isn't blown