Approximately 5-volts are applied to the Intake Air Temperature (IAT) Sensor output terminal from the PCM via the resistor in the PCM. The ground terminal is grounded with PCM. The sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, the resistance decreases. The sensor output voltage increases when the resistance increases and decreases when the resistance decreases.
Removal & Installation
- Disconnect the negative battery cable.
Replacing the sensor requires disconnecting the electrical connector, then carefully removing the lid of the air filter housing.
NOTEHandle the sensor assembly carefully, protecting it from impact, extremes of temperature and/or exposure to shop chemicals.
- Installation is the reverse of the removal procedure.
- Disconnect the sensor connector.
- Measure the resistance between the sensor side connector terminals 1 and 4.
- Should be 13-17 Kohms at -4°F
- Should be 5.3-6.7 Kohms at 32°F
- Should be 2.3-3.0 Kohms at 68°F
- Should be 1.0-1.5 Kohms at 104°F
- Should be 0.56-0.76 Kohms at 140°F
- Should be 0.30-0.45 Kohms at 176°F
Measure resistance while heating the sensor using warm, dry air.
As the temperature rises, the resistance value should drop.
If within specifications, replace the ECM or PCM.
NOTECheck that the circuit is not Open circuit.
- If no continuity, replace the Mass Air Flow (MAF) Sensor.
- If continuity, turn the ignition switch to "ON" position and measure the voltage between terminal 1 and ground on the harness side of the sensor connector. Voltage should be between 4.5 and 4.9 volts.
- Turn the ignition switch to "LOCK" (OFF) position and check for the resistance between terminal 4 and ground. Resistance should be less than 2 ohm.
- If any check above does not meet the specifications, check connectors and wiring between the sensor and ECM/PCM. If ok, replace ECM/PCM.