Pressure Switch
WARNING: This page is about a different car, the 2002 Isuzu Rodeo Sport. However, it is still accessible from the selected car via links, so may be relevant.
When hydraulic pressure reaches 3430 kPa (500 psi), the pressure switch closes causing the Powertrain Control Module (PCM) to actuate the throttle valve, which increases the engine rpm to prevent the overload-induced engine speed slow down. The switch opens when hydraulic pressure drops to 2940 kPa (430 psi).