B2647

DTC B2647

CIRCUIT DESCRIPTION




The ambient light sensor indicates the light level to control the automatic headlamps and park lamps. The body control module (BCM) provides a 5-volt reference signal to the light sensor through the ambient light sensor signal circuit. The BCM receives the modified voltage from the ambient light sensor through the ambient light sensor low reference circuit. A low voltage under 1.5 volts, signals a dark condition to the BCM and vice versa.

CONDITIONS FOR RUNNING THE DTC
The ignition switch is in the ON position.

CONDITIONS FOR SETTING THE DTC
Any of the following conditions will set this DTC:
- The ambient light sensor signal reference circuit is open for 5 seconds.
- The ambient light sensor signal reference circuit is shorted to ground for 5 seconds.
- The ambient light sensor signal return circuit is open for 5 seconds.
- The ambient light sensor signal return circuit is shorted to ground for 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
The headlamps and park lamps are always illuminated with the ignition ON.

CONDITIONS FOR CLEARING THE DTC
- The conditions for setting the DTC are no longer present.
- A history DTC clears after 100 malfunction free ignition cycles.
- The BCM receives the clear code command from the scan tool.

DIAGNOSTIC AIDS
If the DTC is a history DTC, the problem may be intermittent.

TEST DESCRIPTION

Steps 1-11:

The numbers below refer to the step numbers on the diagnostic table.
2. The normal operating voltage of the ambient light sensor (photocell) is 0.5-4.5 volts.
3. This step determines if there is a problem with the signal circuit of the ambient light sensor.