Manifold Absolute Pressure (MAP) Output Check

Manifold Absolute Pressure Output Check:

Wiring Diagram For Manifold Absolute Pressure Output Check:

MANIFOLD ABSOLUTE PRESSURE (MAP) OUTPUT CHECK

CIRCUIT DESCRIPTION:

The Manifold Absolute Pressure (MAP) sensor measures the changes in the intake manifold pressure which result from engine load (vacuum) and rpm changes; and converts these into a voltage output. It sends that output voltage to the PCM and is used for fuel calculation. The MAP sensor is also used to determine the barometric pressure, allowing the PCM to make adjustments for different altitudes.



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

1. Checks MAP sensor output voltage to the PCM. This voltage, without engine running, represents a barometer reading to the PCM.



2. Applying 34 kPa (10" Hg.) vacuum to the MAP sensor should cause the voltage to be 1.2 - 2.3 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 restriction. Be sure no other vacuum devices are connected tot he MAP hose.

4. Disconnect sensor from bracket and twist sensor by hand (only) to check for intermittent connection between harness and sensor. Output changes greater than .1 volt indicate a bad connector or connection. If OK replace sensor.