Diagnostic Aids
WARNING: This page is about a different car, the 2002 Saturn LW200, 2002 Saturn L200, and 2002 Saturn L100. However, it is still accessible from the selected car via links, so may be relevant.
To locate an intermittent problem, use Scan tool to monitor CRUISE BRAKE/CLUTCH SW with brake pedal released while wiggling wires. The Scan tool will read APPLIED when ignition voltage is present at the PCM brake switch input. Wiggling wires while watching for a change from RELEASED to APPLIED may locate the area where a shorted switch or short to voltage in the wiring could lie.
The stoplight switch should be open across its terminals when the plunger is all the way in.