CTS 2003-2005

Manifold Absolute Pressure Sensor

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Operation



The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). The MAP sensor signal voltage to the PCM varies from below 2 volts at idle (high vacuum) to above 4 volts with the ignition switch ON , engine not running or at wide-open throttle (low vacuum).

If the PCM detects a voltage that is lower than the possible range of the MAP sensor, a Diagnostic Trouble Code (DTC) will be set. A signal voltage higher than the possible range of the sensor will also set a DTC. An intermittent low or high voltage will also set DTCs. The PCM can also detect a shifted MAP sensor. The PCM compares the MAP sensor signal to a calculated MAP based on throttle position and various engine load factors. If the PCM detects a MAP signal that varies excessively above or below the calculated value, a DTC will be set. The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the PCM to automatically adjust for different altitudes.

Removal & Installation



  1. Disconnect the negative battery cable.
  2.  
  3. Locate the MAP sensor and remove the retaining screws
  4.  
  5. Detach the electrical connector.
  6.  



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Fig. On the 3.1L engine, the MAP sensor is located alongside the intake manifold



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Fig. MAP sensor and its bracket arrangement-3.4L (VIN E) engine



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Fig. Location of the MAP sensor on the throttle body adapter-3.4L (VIN X) Engine



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Fig. The MAP sensor is located just behind the throttle body mounting base-3.5L (VIN H) engine



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Fig. MAP sensor and its location alongside the supercharger-3.8L (VIN 1) Engine



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Fig. On the 3.8L (VIN K) engine, the MAP sensor is located on top of the PCV valve cover

  1. Remove the vacuum hose and lift the MAP sensor from the engine.
  2.  
  3. Installation is reverse of the removal procedure.
  4.  

Testing



As with most all engine control sensors used in your vehicle, a thorough and proper test can only be performed by a qualified technician using a scan tool to read the data stream from the PCM. There are a few items a non-professional should check before taking the vehicle to a qualified technician for diagnosis and repair.



Check for poor connection at the PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections.
 
Look for a damaged harness or damaged wiring going to the MAP sensor, especially if heavy work has recently been done where the connector could have been damaged.
 
The vacuum hose can deteriorate with age and should always be checked carefully if a MAP problem is suspected.
 

 
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