S10/T10 P/U 2WD L4-151 2.5L (1988)
Power Steering Pressure Switch: Description and Operation
The power steering pressure switch is used on 4 cylinder models and opens during high pressure power steering situations. When the power steering
switch is open, power to the A/C relay is shut off, resulting in compressor clutch disengagement. A signal is also sent to the ECM. The ECM uses this
signal for idle control.