Expedition 4WD V8-5.4L VIN 5 (2006)
Power Steering Pressure Switch: Description and Operation
Power Steering Pressure (PSP) Switch
POWER STEERING PRESSURE (PSP) SWITCH
Typical Power Steering Pressure (PSP) Switch
The PSP switch monitors the hydraulic pressure within the power steering system. The PSP switch is a normally closed switch that opens as the hydraulic
pressure increases. The PCM provides a low current voltage on the PSP circuit. When the PSP switch is closed, this voltage is pulled low through the
SIG RTN circuit. The PCM uses the input signal from the PSP switch to compensate for additional loads on the engine by adjusting the idle RPM and
preventing engine stall during parking maneuvers. Also, the PSP switch signals the PCM to adjust the transmission electronic pressure control (EPC)
pressure during increased engine load, for example during parking maneuvers.
