ECM DTC EO31: Shorted Map Sensor Circuit: Description

The manifold absolute pressure sensor (MAP) is a "3-Wire" sensor, a potentiometer that change resistance based upon manifold vacuum. The ECM provides a 5 volt reference on CKT 474 and ground on CKT 476. The MAP signal (CKT 432) varies between ground and 5 volts as manifold vacuum varies. 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 a low MAP reading indicates a light load. Code EO31 sets when the ECM detects a MAP sensor signal too high (MAP value greater than 108 kPa). Possible causes of Code EO31 are, Short to voltage on CKT 432. Open from sensor to ECM on CKT 476. Defective MAP sensor.