ECM Code EO31: Shorted Map Sensor Circuit: Action:

ECM turns on SERVICE ENGINE SOON light, uses a substitute MAP sensor value from MAP versus RPM table when throttle switch is closed and assumes barometric pressure value is 92.2 kPa. The MAP sensor output signal voltage is a D voltage varying with manifold 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 to indicate engine load. A high MAP reading indicates heavy load and low MAP indicates low load. Code EO31 is designed to set when ECM detects a MAP sensor signal out of high limits.

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

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

Test Number 2) This checks for an open circuit from terminal "A" of sensor connector to ECM terminal A5 (ground). If ground is open, sensor cannot divide reference voltage to make signal voltage vary. The signal voltage is always high.