2010 Cadillac CTS Sedan AWD V6-3.6L Page 193
Circuit Description
The vehicle uses left and right sunload sensors that are integrated into one sensor assembly along with the ambient light sensor. Low reference and
signal circuits enable the sensor to operate. The sensor signal varies between 0 and 5 volts. The HVAC control module converts the signal to a
range between 0 and 255 counts. The sunload sensor provides the HVAC control module with a measurement of the amount of light shining on the
vehicle. Bright or high intensity light causes the vehicles interior temperature to increase. The HVAC system compensates for the increased
temperature by diverting additional cool air into the vehicle.
The following DTCs are for the left and right sunload sensors.
* B0183 is for the left sunload sensor.
* B0188 is for the right sunload sensor.
Conditions for Running the DTC
Ignition ON.
Conditions for Setting the DTC
The HVAC control module detects the signal circuit is less than 5 counts or greater than 250 counts.
Action Taken When the DTC Sets
* The driver information center (DIC) will display SERVICE A/C SYSTEM.
* If the DTC is set the system will act as if no sunload condition exists.
Conditions for Clearing the DTC
* The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.
* The history DTC will clear after 50 fault-free ignition cycles.
Reference Information
Schematic Reference
HVAC Schematics (See: Heating and Air Conditioning/Diagrams/Electrical Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Automatic HVAC Description and Operation (See: Heating and Air Conditioning/Description and Operation/HVAC - Automatic)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, observe the appropriate scan tool Sunload Sensor parameter. The reading should be between 5 and 250 counts and change with
sunlight changes.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the sunload sensor.
2. Test for less than 10 ohms between the ground circuit terminal C and ground.
瀚慖f greater than the specified range, test the ground circuit for an open/high resistance.
