B0514

DTC B0173, B0178, B0509, B0514, B0519, B3583, or B3933

Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- 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 °C (-40 to +185 °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 [1][2]Electrical Diagrams

Connector End View Reference
Component Connector End Views

Description and Operation
Automatic HVAC Description and Operation Description and Operation

Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs

Scan Tool Reference
Control Module References 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 °C (9 °F) difference of appropriate Duct Actual parameter value.

Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
2. Test for less than 10 ohm between the temperature sensor ground circuit terminal B and ground.
3. If greater than the specified value, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
4. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground.
5. If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K33 HVAC Control Module.
6. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K33 HVAC Control Module.
7. If all circuits test normal, replace the temperature sensor. Repair Instructions

Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

- HVAC Component Replacement Reference
- Control Module References