Code 31, Map Sensor, Open Or Shorted Circuit: Notes

The MAP sensor responds to changes in manifold pressure. ECM receives a signal voltage that varies between 1-1.5 volts at closed throttle idle, to approximately 4-4.5 volts at wide open throttle (low vacuum). If MAP sensor fails, ECM substitutes a fixed MAP value and uses TPS to control fuel delivery.

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

Verifies 5-volt reference is available from ECM.
Verifies ECM is grounding the circuit.