B0179

DTC B0164, B0174, or B0179

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 Descriptor
DTC B0164 05
- Passenger Compartment Temp Sensor 1 Circuit Short to Battery or Open

DTC B0164 06
- Passenger Compartment Temp Sensor 1 Circuit Short to Ground or Open

DTC B0174 05
- Output Air Temperature Sensor 1 Circuit Short to Battery or Open

DTC B0174 06
- Output Air Temperature Sensor 1 Circuit Short to Ground or Open

DTC B0179 05
- Output Air Temperature Sensor 2 Circuit Short to Battery or Open

DTC B0179 06
- Output Air Temperature Sensor 2 Circuit Short to Ground or Open

Diagnostic Fault Information






Circuit/System Description

Inside Air Temperature Sensor

The inside air temperature sensor is internal to the HVAC control module.

Upper and Lower Air Duct Temperature Sensors

The HVAC control module supplies the air duct temperature sensors with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

The HVAC control module detects the air temperature sensor signal circuit is less than 5 counts or greater than 250 counts.

Action Taken When the DTC Sets

The Auto feature of the HVAC control module will be inoperative.

Conditions for Clearing the DTC

* The DTC will become history if the HVAC control module no longer detects a failure.
* The history DTC will clear after 100 fault-free ignition cycles.

Reference Information
Schematic Reference

HVAC Schematics HVAC - Automatic
Connector End View Reference

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

* Air Temperature Description and Operation Air Temperature
* Air Delivery Description and Operation Air Delivery

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

DTC B1064

Verify DTC B1064 is not set.

If the DTC is set, replace the HVAC control module.

DTC B0174 or B0179

Ignition ON, observe the appropriate scan tool Duct Air Temp. Sensor parameter. The reading should be between 5 and 250 counts and change with inside passenger compartment or upper or lower air duct air temperature changes.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate air duct temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, verify that both the appropriate scan tool Duct Air Temp. Sensor parameter is less than 5 counts.

• If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.

4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the appropriate scan tool Duct Air Temp. Sensor parameter is greater than 250 counts.

• If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. If all circuits test normal, test or replace the appropriate air temperature sensor.

Repair Instructions

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

* Duct Air Temperature Sensor Replacement - Upper Duct Air Temperature Sensor Replacement - Upper
* Control Module References Programming and Relearning for HVAC control module replacement, setup, and programming