Powertrain Controls - ECM/PCM

Diagnostic Chart:

Circuit Schematic:

Temperature - Resistance Chart For Sensors:

IAT CIRCUIT-TEMPERATURE OUT OF RANGE LOW
The inlet air temperature (IAT) sensor is a thermistor located in the air intake passage of the air induction system on the engine. When the sensor is cold it has a high resistance, the resistance decreases as the temperature of the sensor increases. The PCM supplies a five volt signal to the sensor which is also connected to ground. The PCM reads the voltage drop on the sensor signal line to determine air temperature.

DTC PARAMETERS
DTC 23 will set if the PCM sees IAT temperature less than -30°C (-22°F).

DIAGNOSTIC AIDS
Refer to Temperature vs. Resistance chart.

When attempting to diagnose an intermittent problem, use the Scan tool[1] to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.

Check the tightness of the female terminal grip with a spare male terminal.

^ This DTC may be set if the vehicle has been in extremely cold ambients. Ask the customer if this has occurred.
^ DTC 23 will set if the IAT is disconnected and the ignition is cycled On.
^ IAT may be compared to ECT temperature, with a Scan tool, if engine has been cooled overnight at ambient temperature. They should be within four degrees of each other with ignition On and engine Off.

[1]Select Malfunction History from Scan tool Engine Control (EC) menu.