Chart C-1E, Power Steering Pressure Switch
Power steering pressure switch is normally open to ground and circuit No. 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 No. 495 to read less than one volt. The ECM will increase the idle air rate and retard the timing. Pressure switch that will not close, or an open circuit No. 450 or 495 may cause the engine to stop when power steering loads are high. A switch that will not open, or a shorted to ground circuit No. 450 or 495, will cause timing to retard at idle, and may affect idle quality.
- This test checks for ECM signal voltage on circuit No. 495, and confirms that ground circuit No. 450 is okay.
- Checks to determine if circuit No. 495 is shorted to ground.
- This should simulate a closed switch.