Chart C-1D: Map Output Check

The manifold absolute pressure sensor (MAP) measures manifold pressure (vacuum) and sends that signal to the ECM. The MAP sensor is mainly used for fuel calculation, when the ECM is running in the throttle body back-up mode. The MAP sensor is also used to determine the barometric pressure and to help calculate fuel delivery.

1. Checks MAP sensor output voltage to the ECM. This voltage, without engine running, represents a barometer reading to the ECM.
2. Applying 10" hg (34 kPa) vacuum to the MAP sensor should cause the voltage to be 1.2 volts less than the voltage at test 1). When applying vacuum to the sensor, the change in voltage should be instantaneous. A slow voltage change indicates a faulty sensor.
3. Check vacuum hose to sensor for leaking air restriction. Be sure no other vacuum devices are on or connected to the MAP hose.

Fig 1: Chart C-1D: MAP Output Check Flow Chart

Fig 2: Chart C-1D: MAP Output Check Flow Chart

Fig 3: Chart C-1D: MAP Output Check Schematic