Sensors and Switches - Manifold Pressure/Vacuum Sensor Location
Manifold Pressure/Vacuum Sensor: Description and Operation
MAP Sensor Circuit
Purpose:
The Manifold Absolute Pressure (MAP) sensor is used to monitor the amount of vacuum in the EGR circuit. The MAP senses the actual vacuum
in the EGR vacuum line and relays a voltage signal to the ECM. The signal is compared to the EGR duty cycle calculated by the ECM.
If there is a difference in the ECM command and what is at the EGR valve sensed by the MAP, the ECM makes minor adjustments to correct.
When a major difference is sensed, the ECM recognizes a fault and sends a full EGR signal.
Operation:
The computer sends a 5 volt reference signal to the MAP sensor. As vacuum changes occur in the EGR supply line, the electrical resistance of the
MAP sensor also changes. By monitoring the sensor output voltage, the computer can determine the EGR line vacuum.
The ECM energizes or de-energizes the EGR solenoid and/or EGR vent solenoid to control EGR valve function based upon the input of the MAP
sensor.
Location:
The MAP sensor is mounted on the left side of the cowl.
