E040

TEST CONDITIONS
1. Vehicle speed equal to or greater than 0 MPH;
2. Engine running

FAILURE CONDITIONS
Power steering pressure equal to or greater than 955 kPa or Power steering pressure less than or equal to 12.

ACTION TAKEN
1. ECM turns on "Engine Control System Fault" telltale;
2. ECM commands BCM to display "Service Soon" message on Driver Information Center (DIC).

DESCRIPTION
The power steering pressure sensor is a "3-wire sensor" or potentiometer with a 5 volt reference input from the ECM to the sensor on CKT 474 and a reference ground to the ECM on CKT 1076. CKT 815 is the output signal to the ECM from the sensor and it varies between 0 and 5 volts based upon power steering pressure. As the pressure increases the signal voltage increases and as the pressure decreases, signal voltage decreases. The ECM uses power steering pressure information to help idle stability when power steering loads are put on the engine.

Code EO40 will set when the ECM sees a high pressure signal or low pressure signal at a vehicle speed of equal to or greater than 0 MPH with the engine running.

Notes on Fault Tree
1. With a Code EO40 present, power steering parameter ED19 will read high or low. If not, then the fault is not preset at this time. See "Notes on Intermittents".
2. Checking for open in CKT 815.

Notes on Intermittents
Observe ECM parameter ED19. Power steering pressure should be between 12-100 at no load (idle) and between 750 and 999 at full lock.

At idle, manipulate affected wiring while observing ECM Data ED19. If the parameter jumps to full value or skips to zero, repair intermittent open or short to ground in the wiring. Disconnect and reconnect power steering sensor and ECM connectors and ensure they are latched. If wiring and connector check out ok, substitute a known good power steering sensor and retest.