Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Power Steering Pressure Switch: Description and Operation
Power Steering Pump Pressure Switch
POWER STEERING PRESSURE SWITCH-PCM INPUT
A pressure sensing switch is included in the power steering system (mounted on the high-pressure line). This switch will be on vehicles equipped
with power steering. The switch (Fig. 9) provides an input to the Powertrain Control Module (PCM). This input is provided during periods of high
pump load and low engine rpm; such as during parking maneuvers. The PCM will then increase the idle speed through the Idle Air Control (IAC)
motor. This is done to prevent the engine from stalling under the increased load.
When steering pump pressure exceeds 3275 kPa +/- 690 kPa (475 psi +/- 100 psi), the normally closed switch will open and the PCM will
increase the engine idle speed. This will prevent the engine from stalling.
When steering pump pressure drops below approximately 70 psi, the switch circuit will close and engine idle speed will return to its previous
setting.
