B1318

DTC B1318

CIRCUIT DESCRIPTION
The instrument panel module (IPM) monitors ambient light with the left and right sunload sensors. The sunload sensors are an infrared light sensitive photodiode. The IPM supplies 5 volts to the sunload sensors signal circuit and provides a low reference circuit. As the light shining upon the sensor gets brighter, the sensor conductance increases. The sensor signal decreases as the conductance increases. The IPM uses this information to compensate for the effect of the sun on the inside air temperature of the vehicle. The IPM converts the voltage values to count values where one volt is approximately equal to 51 counts.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC B1318 Left Sunload Sensor
- DTC B1328 Right Sunload Sensor

CONDITIONS FOR RUNNING THE DTC
The ignition is ON.

CONDITIONS FOR SETTING THE DTC
The IPM detects the sunload sensor signal circuit is less than 0.09 volt (5 counts) or more than 4.90 volts (250 counts).

ACTION TAKEN WHEN THE DTC SETS
A default value of 240 counts will be substituted for the sensor data by the IPM.
- Left sunload sensor
- The Driver Solar displayed on the scan tool in the HVAC Sensors data list will be the default value.
- The Left Solar Sensor displayed on the scan tool in the Open/Short data list will be the actual value.
- Right sunload sensor
- The Passenger Solar displayed on the scan tool in the HVAC Sensor data list will be the default value.
- The Right Solar Sensor displayed on the scan tool in the Open/Short data list will be the actual value.

CONDITIONS FOR CLEARING THE DTC
- The DTC will become history if the IPM no longer detects a failure.
- The history DTC will clear after 50 fault-free ignition cycles.
- The DTC can be cleared by using a scan tool.

TEST DESCRIPTION

Steps 1 - 11:

Step 12:

The numbers below refer to the step numbers on the diagnostic table.
2. The operating range of the sensor is between 0.09 -4.90 volts. If the scan tool displays a value between 0 - 0.08 volt or 4.91 - 5.0 volts, then the sensor is performing outside of its designed limits.
3. Tests for the proper operation of the circuit in the high voltage range.
4. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
5. Tests the sensor signal circuit for a short to ground.
6. Tests the sensor signal circuit for a short to voltage, a high resistance, or an open.
7. Tests the low reference circuit for a high resistance or an open.