9-3 1999

Air Charge Temperature Sensor

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Location





Click image to see an enlarged view

Fig. ACT sensor (1) and fastener (2) location

Operation



The Air Charge Temperature (ACT) Sensor is a Negative Temperature Coefficient (NTC) Thermistor that monitors the intake air temperature. The ACT 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 the measured intake air temperature. The PCM uses data from the ACT Sensor to calculate air-fuel mixture, ignition timing, and fuel injector pulse width.

Removal & Installation



2.0L Engine
  1. Before servicing the vehicle, refer to the precautions.
  2.  
  3. Unplug the sensor connector.
  4.  
  5. Remove the sensor.
  6.  

To install:

  1. Installation is the reverse of removal.
  2.  
  3. Check the O-rings and install new ones if necessary.
  4.  
  5. Lubricate the threads of the sensor with Vaseline.
  6.  
  7. Spray the connector with Kontakt 61, part no. (16) 30 04 520.
  8.  

2.3L Engine
  1. Before servicing the vehicle, refer to the precautions.
  2.  
  3. Unplug the sensor connector.
  4.  
  5. Remove the sensor.
  6.  

To install:

  1. Installation is the reverse of removal.
  2.  
  3. Check the O-rings and install new ones if necessary.
  4.  
  5. Lubricate the threads of the sensor with Vaseline.
  6.  
  7. Spray the connector with Kontakt 61, part no. (16) 30 04 520.
  8.  

Testing



Specific to:

Saab 9000 1998

Saab 9-3 1999-2005

Saab 9-5 1999-2005


NOTE
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

ACT Circuit Testing

Specific to:

Saab 9000 1998

Saab 9-3 1999-2005

Saab 9-5 1999-2005

Use a suitable scan tool, a Graphing Multi-Meter (GMM), or a Digital Volt-Ohm Meter (DVOM) in order to view the ACT data.

ACT Sensor logic is relative to the scale of resistance: when the intake air temperature is low, the voltage is increased. When the coolant temperature is high, the voltage is decreased (See Figure 1).

Inspect the air intake tube, the engine air filter, and the MAF and/or BARO/ACT sensors 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 ACT Sensor to verify the signal with a DVOM, and verify PCM communication before replacing the ACT Sensor.

Click image to see an enlarged view

Fig. Figure 1: ACT Sensor Range Chart

ACT Sensor Strategy

Specific to:

Saab 9000 1998

Saab 9-3 1999-2005

Saab 9-5 1999-2005

The ACT Sensor provides a linear input signal (See Figure 1) to the Powertrain Control Module (PCM) for a number of engine control system calculations. The ACT signal is compared with Manifold Absolute Pressure (MAP), Mass Air Flow (MAF), Engine Coolant Temperature (ECT), and Fuel Trim (HO2S) in order to determine the correct air-fuel mixture for measured operating conditions.

Connection & Wiring Diagnosis

Specific to:

Saab 9000 1998

Saab 9-3 1999-2005

Saab 9-5 1999-2005

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.

  1. Test the wiring harness and connectors by performing the following tests:

    Move the related connectors and wiring while monitoring the appropriate scan tool data.
     
    Move the related connectors and wiring with the component commanded ON and OFF. Using a suitable the scan tool, observe the component operation.
     
    With the engine running, move the related connectors and wiring while monitoring component operation.
     
    If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary.
     

  2.  
  3. 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.
     
    Inspect for improperly formed or damaged terminals and test for incorrect terminal tension.
     
    Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body.
     
    Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and/or brittle sections of wire in the suspect circuits.
     
    Inspect for wires that are broken inside the insulation by gently pulling on suspect sections of wiring.
     

  4.  

Specific to:

Saab 9-3 1999-2005

Saab 9-5 1999-2005

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.

  1. Test the wiring harness and connectors by performing the following tests:

    Move the related connectors and wiring while monitoring the appropriate scan tool data.  
     
    Move the related connectors and wiring with the component commanded ON and OFF. Using a suitable the scan tool, observe the component operation.
     
    With the engine running, move the related connectors and wiring while monitoring component operation.
     
    If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary.
     

  2.  
  3. 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.  
     
    Inspect for improperly formed or damaged terminals and test for incorrect terminal tension.  
     
    Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body.  
     
    Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and/or brittle sections of wire in the suspect circuits.  
     
    Inspect for wires that are broken inside the insulation by gently pulling on suspect sections of wiring.
     

  4.  

Related Diagnostic Trouble Codes

Specific to:

Saab 9000 1998

Saab 9-3 1999-2005

Saab 9-5 1999-2005



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

 
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