Cherokee 2WD L4-150 2.5L VIN H TBI (1988)
Power Steering Pressure Switch: Description and Operation
Power Steering Pump High Pressure Switch
This switch senses the pressure of the power steering system and works in conjunction with the air conditioning system and the ECU to adjust the engine
rpm when the engine load is high and the engine speed is low (i.e. when the vehicle is being parked).
When the power steering system pressure exceeds 1896 kPa +/- 172 kPa (275 psi +/- 25 psi), with the A/C compressor clutch not engaged, the ECU will
increase the idle rpm via the Idle Speed Actuator (ISA) Motor so that the engine will not stall.
When the power steering system pressure exceeds 1896 kPa +/- 172 kPa (275 psi +/- 25 psi), with the A/C compressor clutch engaged, the ECU will
disengage the A/C compressor clutch by removing the ground to the A/C compressor clutch relay. This will lighten the load on the engine so that the
engine does not stall.
The ECU looks at the A/C select and request signal circuits to determine if the A/C compressor clutch has been engaged.
