Operation
Specific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
The Intake Air Temperature (IAT) Sensor is a Negative Temperature Coefficient (NTC) Thermistor that monitors the intake air temperature. The IAT 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 engine intake air temperature. The PCM uses data from the IAT Sensor to calculate air-fuel mixture, ignition timing, and fuel injector pulse width. The IAT Sensor is sometimes integrated with the Mass Air Flow (MAF) Sensor as a physical component.
Removal & Installation
Specific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
- Before servicing the vehicle, refer to the Precautions Section.
- Disconnect the negative battery cable.
- Disconnect the Intake Air Temperature (IAT) sensor electrical connector.
-
Remove the IAT sensor from the clean air duct.
Fig. Intake Air Temperature (IAT) sensor location
To install:
-
Install the IAT sensor and ensure the correct sensor orientation.
Fig. Showing the correct IAT sensor orientation
- Attach the IAT sensor electrical connector.
- Connect the negative battery cable.
Testing
Specific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
Connection & Wiring Diagnosis
Specific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
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.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.
-
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.
Specific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
Use a suitable scan tool, a Graphing Multi-Meter (GMM), or a Digital Volt-Ohm Meter (DVOM) in order to view the IAT data.
IAT 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 IAT 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 IAT Sensor to verify the signal with a DVOM, and verify PCM communication before replacing the IAT Sensor.
Fig. IAT Sensor Range Chart
Specific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
The IAT Sensor provides a linear input signal (See Figure 1) to the Powertrain Control Module (PCM) for a number of engine control system calculations. The IAT 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.
Related Diagnostic Trouble CodesSpecific to:
Jeep Compass 2007-2009
Jeep Patriot 2007-2009
Fig. Related Diagnostic Trouble Codes
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