GM Service Manual Online
For 1990-2009 cars only

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 B0159: Outside Air Temperature Sensor Circuit Range/Performance

DTC B0164: Passenger Compartment Temperature Sensor 1 Circuit Range/Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ambient Air Temperature Sensor Signal

B0159

B0159

B0159

--

Inside Air Temperature Sensor

B0164

B0164

B0164

--

Low Reference

--

B0159, B0164

B0159, B0164

--

Circuit/System Description

The ambient air temperature sensor allows the HVAC control module to monitor the temperature of the air surrounding the front of the vehicle. The inside air temperature sensor assembly allows the HVAC control module to monitor the temperature of the air inside the passenger compartment. The module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The module provides ground to the air temperature sensors through the low reference circuits. The HVAC control module monitors the voltage drops across the air temperature sensors and uses the inputs for automatic control calculations. The HVAC control module also uses the ambient air temperature input to calculate the value of the ambient air temperature display. When the air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the air temperatures are hot, the resistances of the sensors are low and the voltage signals are low.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

    • The HVAC control module detects the sensor signal circuit is less than -35°C (-39°F).
    • The HVAC control module detects the sensor signal circuit is more than 85°C (185°F) .

Action Taken When the DTC Sets

The HVAC control module uses a default air temperature value for further automatic control calculations. The default values are not displayed on the scan tool.

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

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Air Temperature Description and Operation
    •  Air Delivery 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

Ignition ON, observe the appropriate scan tool Air Temp. Sensor parameter. The reading should be between -35°C (-39°F) and 85°C (185°F) and change with air temperature changes.

Circuit/System Testing

Important: An instant OAT update must be performed by pressing the A/C and Recirc buttons at the same time before and after the system has been serviced to update the filtered ambient air temperature sensor.

  1. Ignition OFF, disconnect the harness connector at the appropriate air temperature sensor.
  2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground.
  3. 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.
  4. Ignition ON, verify the scan tool Air Temp Sensor parameter is less than -35°C (-39°F).
  5. 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.
  6. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Air Temp Sensor Raw parameter is greater than 85°C (185°F).
  7. 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.
  8. If all circuits test normal, test or replace the air temperature sensor.

Component Testing

  1. Test the air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
  2. Compare the readings with the Temperature VS Resistance table Sensor Resistance Table and verify that the resistance is within 5 percent of the specification.
  3. If not within the specified range, replace the sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Inside Air Temperature Sensor Replacement
    •  Ambient Air Temperature Sensor Replacement
    •  Control Module References for HVAC control module replacement, setup, and programming