DTC B119: Twilight Photocell Circuit: Description

The twilight sensor uses a photocell to control the signal voltage to the BCM. The BCM applies a voltage on circuit No. 278 to the sensor. When the sensor detects darkness, its resistance is high, therefore, the BCM will see a high signal voltage. As the sensor detects light, its resistance becomes less and the signal voltage is pulled low through the ground circuit No. 736. This signal voltage will vary between 5 volts (open circuit) and zero (0) volts (shorted circuit).

Code B119 will set if the ignition is on and the signal voltage indicates more than 94% (open circuit) or less than 6% (shorted circuit). During the time the failure is present, a substitute light reading (indicating darkness) will be implemented to allow continued operation of the headlights. The measure of light reading (BD44) will, however, display the actual sensor reading.