B3583

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

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Automatic HVAC Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (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°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.

• 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.

3. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground.

• 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.
• 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.

4. If all circuits test normal, replace the temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* HVAC Component Replacement Reference (Removal and Replacement)
* Control Module References (Programming and Relearning)