2010 Cadillac Truck SRX FWD V6-3.0L Page 738

2010 Cadillac Truck SRX FWD V6-3.0L Page 738

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC B0173 02

- Upper Left Duct Air Temperature Sensor Circuit Short to Ground

DTC B0173 05

- Upper Left Duct Air Temperature Sensor Circuit High Voltage/Open

DTC B0178 02

- Lower Left Duct Air Temperature Sensor Circuit Short to Ground

DTC B0178 05

- Lower Left Duct Air Temperature Sensor Circuit High Voltage/Open

DTC B0509 02

- Upper Right Duct Air Temperature Sensor Circuit Short to Ground

DTC B0509 05

- Upper Right Duct Air Temperature Sensor Circuit High Voltage/Open

DTC B0514 02

- Lower Right Duct Air Temperature Sensor Circuit Short to Ground

DTC B0514 05

- Lower Right Duct Air Temperature Sensor Circuit High Voltage/Open

DTC B0519 02

- Rear Upper Duct Air Temperature Sensor Circuit Short to Ground

DTC B0519 05

- Rear Upper Duct Air Temperature Sensor Circuit High Voltage/Open

DTC B3583 02

- Rear Lower Duct Air Temperature Sensor Circuit Short to Ground

DTC B3583 05

- Rear Lower Duct Air Temperature Sensor Circuit High Voltage/Open

DTC B3933 02

- 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.