DTC 31

Code 31 Chart:

Manifold Absolute Pressure Sensor Wiring Diagram:

CIRCUIT DESCRIPTION:

The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The ECM receives this information as a signal voltage that will vary from about 1 to 1.5 volts, at closed throttle idle, to 4-4.5 volts at Wide Open Throttle (WOT) (low vacuum). If the MAP sensor fails, the ECM will substitute a fixed MAP sensor value and use the Throttle Position Sensor (TPS) to control fuel delivery.

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. This step will determine if Code 31 is the result of a hard failure or an intermittent condition. A Code 31 will set if:

a. Pressure signal indicates greater than 80 kPa (low vacuum).
b. TPS less than 12%.
c. These conditions for a time longer than 5 seconds.
d. No Vehicle Speed Sensor (VSS) signal.

2. This step simulates conditions for a Code 32. If the ECM recognizes the change, the ECM and circuits 416 and 432 are OK. If circuit 469 is open, there may also be stored Code 25.

DIAGNOSTIC AIDS:

A Code 31 will result if circuit 469 is open, or if circuit 432 is shorted to voltage or to circuit 416. If Code 31 is intermittent, Testing and Inspection