Manifold Pressure/Vacuum Sensor: Testing and Inspection

Fig. 104 Chart C-1D MAP Output Check:

Fig. 108 - Wiring Diagram for Chart C-1D MAP Output Check. VIN 0, VIN 2, VIN R, VIN U:

CHART C-1D, MAP OUTPUT CHECK

The Manifold Absolute Pressure sensor (MAP) measures manifold pressure (vacuum) and sends that signal to the ECM. The ECM uses this information for fuel and spark control.
1. Checks MAP sensor output voltage to the ECM. This voltage, without engine running, represents a barometer reading to the ECM.
2. Applying 34 kPa (10 inches) vacuum to the MAP sensor should cause the voltage to be 1.2 volts less than the voltage at Step 1. Upon 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 or restrictions. Be sure no other vacuum devices are connected to the MAP hose.