Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Power Steering Pressure Switch: Testing and Inspection
Power Steering Pump Pressure Switch
This switch provides an input to the Powertrain Control Module (PCM). The input is provided during periods of high pump load and low engine
rpm; such as during parking maneuvers. The PCM will then increase 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 circuit will open and the PCM will
increase the engine idle speed.
When power steering pump pressure drops below approximately 70 psi, the switch circuit will close and idle speed will return to normal.
To test switch:
1
Disconnect electrical connector at switch.
2
Connect a pair of jumper wires to switch terminals. Route and secure jumper wires away from fan blades and fan belt.
3
Connect an ohmmeter to jumper wires and observe continuity. Circuit should be closed with engine not running. If continuity is observed, switch is
OK. If switch circuit is open, replace switch.
4
Start engine and observe ohmmeter. With engine at idle speed, continuity should be observed until steering wheel has been turned to left or right
position. Do not hold steering wheel in full left or right position for more than a few seconds. Damage to power steering pump may occur.
5
If continuity is still observed after turning wheel (circuit did not open), replace switch.
