B0185

Schematic:

CIRCUIT DESCRIPTION
The HVAC control module monitors the ambient light on the vehicle via light sensitive photodiode which is called a sunload sensor. The HVAC control module uses this information in order to compensate for the effect of the sun on the inside air temperature of the vehicle. When the sensor is in direct sunlight, the ambient light counts are low. When the sensor is shaded, the ambient light counts are high. The HVAC control module requests engagement of the A/C compressor clutch, and controls the door position of the air temperature actuator in order to maintain the selected air temperature on the HVAC control module.

Conditions for Running the DTC
The ignition is turned ON.

Conditions for Setting the DTC
The HVAC control module detects that the signal circuit is less than 5 Counts.

Action Taken When the DTC Sets
The HVAC control module uses a default sunload sensor value of approximately 0 Counts until the fault is cleared.

Conditions for Clearing the DTC
^ The DTC becomes history when the HVAC control module no longer detects a failure.
^ The history DTC clears after 50 fault-free ignition cycles.
^ The DTC can be cleared with a scan tool.

Diagnostic Aids
^ Insure sun load sensor is in place and secure. Insure no debris around sun load sensor this will give incorrect reading to HVAC control module.
^ If condition is not present refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Steps 1-12:

The number(s) below refer to the step number(s) on the diagnostic table.
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.