The Barometric (BARO) sensor signals the PCM of changes in atmospheric pressure and density to regulate calculated air flow into the engine. The Manifold Absolute Pressure (MAP) sensor monitors and signals the PCM of changes in intake manifold pressure which result from engine load, speed and atmospheric pressure changes.
See Figures 1 and 2
- Connect jumper wires from the sensor connector to the wiring harness. This permits the engine to operate normally while you check the sensor.
- Connect a Digital Volt Ohmmeter (DVOM) between the VREF and SIG RTN terminals of the MAP sensor harness connector. The voltage should be between 4-6 volts.
- If the voltage is not within specification, check the VREF wiring and circuit.
- Probe the SIG RTN and MAP/SIG RTN terminals with the DVOM.
- Unplug the sensor vacuum hose and attach a vacuum testing pump to the sensor.
- With the ignition ON and engine OFF , apply varying amounts of vacuum to the sensor and use the DVOM to measure voltage across terminals.
- If the DVOM voltage reading varies with the varying vacuum, the sensor is functioning properly.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Disengage the electrical connector and the vacuum line from the sensor.
- Unfasten the sensor mounting bolts and remove the sensor.
- Install the sensor with the mounting bolts and tighten.
- Attach the electrical wiring lead to the sensor.
- Attach the vacuum line to the sensor.
- Connect the negative battery cable.