The Manifold Absolute Pressure (MAP) Sensor is a piezoelectric (pressure-sensitive) electronic device that monitors the intake manifold vacuum and atmospheric pressure. The MAP Sensor operates within a 5 volt DC reference range, and provides a linear input signal to the Powertrain Control Module (PCM) that is based upon a comparison of air density and intake manifold vacuum under measured operating conditions. The PCM uses data from the MAP Sensor to calculate air-fuel mixture, ignition timing, and fuel injector pulse width.
Removal & Installation
Before servicing the vehicle, refer to the Precautions Section.
NOTEDisconnecting the negative battery cable on some vehicles may interfere with the functions of the on-board computer systems and may require the computer to undergo a relearning process, once the negative battery cable is reconnected.
NOTEIf working near and/or around the SRS system and components, be sure to properly disable the SRS system. See disarming/arming the SRS system.
- Disconnect the negative battery cable.
- Disconnect the vacuum harness assembly.
- Release the electrical connector.
Remove the bolts or release the MAP sensor locking tabs and remove the sensor.
- Install the bolts or snap sensor onto the bracket.
- Connect the MAP sensor electrical connector.
- Connect the MAP sensor vacuum harness connector.
- Connect the negative battery cable.
- Using the GM diagnostic scan tool or aftermarket equivalent reprogram the necessary systems and components. Be sure to follow the scan tool manufacturer-s directions.
Connection & Wiring Diagnosis
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.
Many intermittent open or short circuits may be caused by wiring harness and connector movement due to vibration, engine torque, bumps and rough pavement, etc.
Test the wiring harness and connectors by performing the following tests:
Move the related connectors and wiring while monitoring the appropriate scan tool data.
Test the connector terminal pins and/or wiring by performing the following tests:
Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body.
Use a suitable scan tool, a Graphing Multi-Meter (GMM), or a Digital Volt-Ohm Meter (DVOM) in order to view the MAP data.
MAP Sensor logic is relative to the scale of resistance: when the manifold absolute pressure is low, the voltage is decreased. When the coolant temperature is high, the voltage is increased.
Inspect the air intake tube, the engine air filter, and the MAP sensor for contamination and physical damage in order to verify that the air induction system is in proper working order. If an air induction system fault is evident, repair as required before continuing.
If a DVOM is being used, additional information may be acquired by taking measurements at the sensor connector as well as the PCM connector. If a significant voltage drop is measured (greater than 0.5 volts DC), check the wiring harness and connections for corrosion, poor pin connections, or damaged wires.
If all engine wiring and pin connections are confirmed, disconnect the MAP Sensor to verify the signal with a DVOM, and verify PCM communication before replacing the MAP Sensor.
The MAP Sensor provides a linear input signal to the Powertrain Control Module (PCM) for a number of engine control system calculations. The MAP signal is compared with Mass Air Flow (MAF), Intake Air Temperature (IAT), and Fuel Trim (HO2S) in order to determine the correct air-fuel mixture for measured operating conditions.Related Diagnostic Trouble Codes