E031

CODE E31

SHORTED MAP SENSOR CIRCUIT

TEST CONDITIONS

Tested continuously

FAILURE CONDITIONS

MAP value 108 kPa greater for more than .0 seconds.

ACTION TAKEN

1. PCM turns on "SERVICE ENGINE SOON" telltale.
2. PCS sets BARO equal 92 kPa.
3. PCM uses a substitute MAP value based on engine rpm and throttle switch status.

DESCRIPTION

The manifold absolute pressure (MAP) is a sensor that changes resitance based upon manifold vacuum. The PCM provides a 5 volt reference and ground. The MAP signal caries between ground and 5 volts as manifold vacuum caries. As MAP decreases, voltage decreases (low engine load, high vacuum). As MAP increases, voltage increases (high engine load, low vacuum). The PCM uses MAP sensor as an indicator of engine load. Code E31 sets when the PCM detects a MAP sensor signal that is too high. The MAP sensor connector is located on the rear top of engine.

NOTES ON FAULT TREE

1. If PCM data P.0.2 goes to 14-16 kPa with the sensor unplugged, the fault is at the sensor or sensor connector.
2. Checking for an open circuit from Pin A of the connector to PCM Pin A5 (ground). If the ground is open, the signal voltage will always be high.

NOTES ON INTERMITTENTS

Manipulate MAP sensor connector, MAP wiring, and PCM connector while observing PCM data P.0.2. Apply and release vacuum to the MAP sensor vacuum port using a vacuum source. If the PCM data P.0.2 immediately jumps to greater than 108 kPA, repair intermittent MAP sensor fault. If wiring and connectors check OK, substitute a known good MAP sensor and retest.