2010 Cadillac Truck SRX FWD V6-3.0L Page 668

2010 Cadillac Truck SRX FWD V6-3.0L Page 668

- Air Conditioning Evaporator Temperature Sensor Circuit Short to Ground

DTC B3933 05

- Air Conditioning Evaporator Temperature Sensor Circuit High Voltage/Open

Circuit/System Description

The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:

* Air temperature sensor - left upper

* Air temperature sensor - left lower

* Air temperature sensor - right upper

* Air temperature sensor - right lower

* Air temperature sensor - rear upper (only with CJ4)

* Air temperature sensor - rear lower (only with CJ4)

* A/C evaporator temperature sensor

A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance

decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 to +85掳C

(-40 to +185掳F). The sensor signal varies between 0-5 V. The HVAC control module converts the signal to a range between 0-255 counts. As the

air temperature increases the count value will decrease. If the HVAC control module detects a malfunctioning sensor, then the control module

software will use a default air temperature value. The default action ensures that the HVAC system can adjust the inside air temperature near the

desired temperature until the condition is corrected.

Conditions for Running the DTC

* Ignition ON.

* The HVAC control module is ON.

Conditions for Setting the DTC

The HVAC control module detects the sensor signal out of range. The signal voltage is less than 0.1 V or greater than 4.9 V for more than 50 ms.

Action Taken When the DTC Sets

The system operates using a default value.

Conditions for Clearing the DTC

The sensor signal is within specified range between 0.1-4.9 V.

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/Connector End Views By Name)

Description and Operation

Automatic HVAC Description and Operation (See: Heating and Air Conditioning/Description and Operation)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit

Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic

Procedures/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General

Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring

Repairs/Wiring Repairs)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Verification

Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct

Actual parameter. The measured temperature should be within 5掳C (9掳F) difference of appropriate Duct Actual parameter value.