Power Steering Pressure Switch: Description and Operation

When hydraulic pressure reaches 3920 ± 690 kPa (570 ± 100 psi), the pressure switch closes causing Engine Control Module (ECM) to actuate the idle air control valve to prevent the overload-induced engine speed down. The switch opens when hydraulic pressure drops to 2970 ± 560 kPa (430 ± 80 psi).