Is the pressure sensor working? Double check it with a multimeter, and make sure you're looking at the sensor the right way (i.e. NO or NC).
Are the wires wired correctly? It's not unheard of for wires to jump one receptacle over during assembly.
When you say the spike LED turns off, that worries me. Is that still happening?
http://content.vexrobotics.com/docs/...uide-sep05.pdf is the Spike Relay user manual; it looks like the PWM port on the sidecar may be misconfigured.