DFI ECM Tests W/Codes: Action:

ECM turns on "ENGINE CONTROL SYSTEM" light. ECM commands BCM to display "SERVICE NOW" message on CCDIC panel. ECM turns off AIR management solenoids. ECM uses a substitute MAP sensor value from MAP versus RPM table when throttle switch is closed. ECM uses a substitute MAP sensor value of 81.8 kPa with open throttle switch. ECM assumes that barometric pressure value is 92.2 kPa.

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 EO31 is designed to set when ECM detects a MAP sensor signal out of high limits, MAP signal at 4.85 volts or more, and having a value greater than 105 kPa.

NOTE: Test numbers refer to test numbers on diagnostic chart.

If ECM parameter ED02 goes to 14-16 kPa with sensor unplugged, fault is at MAP sensor or sensor connector.
This step checks for an open circuit from pin "A" of sensor connector to ECM pin "D12" (ground). If ground is open, sensor cannot divide reference voltage to make signal voltage vary. The signal voltage is always high.