B113

Chart:

Schematic:

DESCRIPTION
The in-car temperature sensor is a thermistor that controls the signal voltage to the Body Control Module (BCM). The BCM applies a voltage on circuit 734 to the sensor. When the sensor is cold its resistance is high, therefore, the BCM will see a high signal voltage. As the sensor warms, its resistance becomes less and the signal voltage is pulled through the sensor ground, circuit 736. This signal leakage will vary between 5 Volts (open CKT) and O Volt (shorted CKT).


Code B113 will set if the ignition is on, the outside temperature sensor has not failed, outside temperature is above -18°C (0°F) and the signal voltage indicates less than -34°C (-29°F) (open CKT) or over 96°C (205°F) (shorted CKT). During the time the failure is present a substitute temperature reading will be implemented to allow continued operation of the climate control system. The in-car temperature reading BD25 will, however, display i.e. actual sensor reading.

TEST DESCRIPTION
The numbers below refer to circled numbers on the diagnostic chart:
1. BCM data value BD25 displays in-car temperature. The normal range is -34°C (-29°F) to 96°C (205°F).
2. Check to see if the open circuit reading is due to the circuit or the sensor. If the open circuit reading changes to a shorted circuit reading after jumping the sensor terminals, the BCM and wiring are OK.
3. By applying a ground to various points in the circuits, an open can be isolated by observing whether the parameter display can be changed from the open reading to the shorted reading.
4. Check to see if the shorted circuit reading is due to the circuit or the sensor. If the shorted circuit reading changes to an open circuit reading after disconnecting the sensor, the BCM and wiring are OK.

NOTE ON INTERMITTENTS
If an intermittent Code B113 is being set, manipulate the related wiring while observing BCM data BD25. If the failure is induced, the reading will jump from its normal value to a reading outside the range of -34C (-29°F) to 96°C (205°F).

If the value displayed by BD25 is not reasonably close to the actual temperature of the air at the sensor, check for proper terminal contact or replace the sensor.