The pressure switch is on the hydraulic unit. I believe its under the brake fluid reservoir. It has a set of 5 wires connecting it. You can test it for continuity also. Let me see if I can help out..
If you shut the car off and pump the brake pedal a dozen times or so to be sure its depressurized, then you should see continuity between pins 3&5, 1&2, 1&4, 2&4 of the part in the hydraulic unit, not the wire harness itself. In particular, pins 1,4 are the switch for the pump motor relay. If 1->4 is zero ohms, then the relay should engage the moment you turn the key on to the run position, and the pump should run. You don't have to start the car to check this. If you see an open circuit, theres your problem. Try tapping on the unit with a hammer and see if anything changes.
The connector has a Grey, Pink/Liteblue, Tan/Red, and 2 other wires whose colors are blurred on my wiring diagram.
Now, if you turn the key on and leave the connector off, you should see 12V on pin 4 (pink/Ltblue) of the wire harness side and 0V on pin 1 (grey wire). pin1 of the harness goes directly to engine ground, so a continuity check to the negative battery post should be 0 Ohms.
Hope this helps.