BCM Code B115, SUNLOAD Temperature Sensor: Notes

The sunload sensor uses a thermistor to control signal voltage to BCM. The BCM supplies and monitors voltage on circuit No. 590 to sensor. When sensor is cold, resistance is high; therefore, BCM will see high signal voltage. As sensor warms, resistance is lowered, signal voltage is pulled low through circuit No. 736 to ground. Signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

Code B115 will set when ignition is on, outside temperature sensor is working properly, ambient temperature is more than -18°C and signal voltage indicates less than -34°C (open circuit) or more than 96°C (short circuit). During a failure, a substitute temperature reading will be used to allow continued operation of A/C-heater system and sunload temperature reading BD32 will display actual sensor reading.

1. BCM parameter BD32 displays sunload temperature. Normal range is -34°C to 96°C.
2. Check to see if open circuit is caused by circuit or sensor. If open circuit reading changes to shorted circuit reading after jumping sensor terminals, BCM and wiring are okay.
3. By applying ground to various points in circuits, an open can be isolated by observing whether parameter display can be changed from open reading to shorted reading.
4. Check to see if short circuit reading is caused by circuit or sensor. If short circuit reading changes to an open circuit reading after disconnecting sensor, BCM and wiring are okay.