Battery Temperature Sensor: Description and Operation
BATTERY TEMPERATURE SENSOR The IAT sensor attaches to the intake air duct (Fig. 1).
The IAT Sensor is a Negative Temperature Coefficient (NTC) Sensor that provides information to the PCM regarding the temperature of the air entering the intake manifold. The PCM sends 5 volts to the sensor and is grounded through the sensor return line. As temperature increases, resistance in the sensor decreases.
Inlet/Intake Air Temperature The inlet air temperature sensor replaces the intake air temperature sensor and the battery temperature sensor. The PCM uses the information from the inlet air temperature sensor along with other stored parameters to determine values to use as an intake air temperature and a battery temperature. The IAT sensor value is used by the PCM to determine air density.
The PCM uses this information to calculate:-Injector pulse width-Adjustment of ignition timing (to prevent spark knock at high intake air temperatures)
Battery Temperature The battery temperature information along with data from monitored line voltage (B+), is used by the PCM to vary the battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures.
The battery temperature information is also used for OBD II diagnostics. Certain faults and OBD II monitors are either enabled or disabled depending upon the battery temperature sensor input (example: disable purge, enable LDP). Most OBD II monitors are disabled below 20 °F.