Astro Van M L4-151 2.5L (1985)
Wiring Diagram For Chart C-1E - Power Steering Pressure Switch Check
CHART C-1E - POWER STEERING (P/S) PRESSURE SWITCH CHECK
Circuit Description:
The power steering pressure switch is normally open to ground, and circuit 495 will be near battery voltage.
Turning the steering wheel increases power steering oil pressure and its load on an idling engine. The pressure switch will close before the load can
cause an idle problem.
Closing the switch causes circuit 495 to read less than 1 volt. The ECM will increase the idle air rate and retard the timing.
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A pressure switch that will not close, or an open CKT 495 or 450, may cause the engine to stop when power steering loads are high.
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A switch that will not open, or a CKT 450 or 495, shorted to ground, will cause timing to retard at idle, and may affect idle quality.
Test Description:
1.
Checks for ECM signal voltage on CKT 495 and confirms that ground CKT 450 is OK.
2.
Maximum resistance, or infinity, indicates an open switch.
3.
Less than 1 ohm indicates that the switch is closed when the power steering pressure is high. Switch is OK.
