Power Steering Pressure Switch: Description and Operation

LOCATION
The power steering pressure switch is mounted on the power steering pump, or high pressure line.

PURPOSE
The switch signals the Powertrain Control Module (PCM) when a power steering load is put on engine.

OPERATION
This switch senses the pressure of the power steering system and sends a signal to the PCM 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), the PCM will increase the idle rpm via the Idle Air Control (IAC) Motor so that the engine will not stall.

CIRCUIT OPERATION
The Power Control Module (PCM) supplies voltage to the Power Steering Pressure switch on circuit K10. Circuit Z12 provides ground for the switch. When the switch closes, voltage flows through the switch to ground on circuit Z12. The switch closes during periods of high power steering pump load and low engine speed; such as parking maneuvers.

Circuit K10 connects to cavity 10 of the PCM. Circuit Z12 terminates at the right rear of the engine.