Circuit Description

The ambient light sensor is an input to the TBC module. TBC module uses the light sensor input to determine the level of light to turn headlights on or off automatically. TBC module monitors the 5-volt reference circuit to light sensor. When TBC module does not see 5 volts on this circuit, DTC will set. TBC also monitors ignition switch position based on ignition signal inputs. TBC performs a self-test on power up.

Conditions for setting DTC:

• Light sensor circuit(s) shorted to ground.
• System voltage 9-16 volts.
• Conditions met for .5 second.