E031

ECM Code E031:

DFI Sensor Circuit:

DESCRIPTION:

The MAP sensor output signal voltage is a DC voltage that varies with manifold absolute pressure. As MAP decreases, voltage decreases (low engine load, high vacuum). As MAP increases, voltage increases (high engine load, low vacuum). The ECM uses MAP sensor values as an indicator of engine load. A high MAP reading indicates heavy load and low MAP reading indicates low load. Code E031 is designed to set when the ECM detects a MAP sensor signal out of limits high - MAP signal at 4.85 volts or more, MAP value greater than 105 kPa.

TEST CONDITIONS:

Always tested.

FAILURE CONDITIONS:

MAP value greater than 105 kPa (106 to 109 kPa) for at least .2 seconds.

ACTION TAKEN:

1. ECM turns on "SERVICE ENGINE SOON" telltale.
2. ECM commands BCM to display "SERVICE CAR SOON" on the CCDIC.
3. Turn off air management solenoids.
4. ECM uses a substitute MAP sensor value from a table of substitute MAP vs RPM when throttle switch is closed.
5. ECM uses a substitute MAP sensor value of 81.8 kPa with open throttle switch.
6. ECM assumes BARO value is 92.2 kPa.

NOTES ON FAULT TREE:

1. If ECM parameter ED02 goes to 14 to 16 kPa with the sensor unplugged, the fault is at the MAP sensor or sensor connector.

2. Checking for an open circuit from Pin A of the sensor connector to ECM Pin D12 (ground). If the ground is open, the sensor can't divide reference voltage to make the signal voltage vary - the signal voltage is always high.

NOTE ON INTERMITTENTS:

Code E031 can be set by:

1. A short to voltage on CKT 432.
2. Open from sensor to ECM on CKT 476.
3. Defective MAP sensor.

Manipulate affected wiring and connectors while observing ECM parameter ED02. Apply and release vacuum to the MAP sensor vacuum port using a vacuum source. If the ECM parameter ED02 displays greater than 105 kPa, the condition has been induced and the cause of the intermittent should be repaired. If wiring and connectors check out OK, substitute a known good MAP sensor and retest.

Review the snapshot data parameters stored with this code to verify failure condition. If the failure condition is verified, check and repair intermittent wiring connection, or sensor.