Service Information

Spark

DTC 2

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 Descriptor

DTC 2: Ambient Air Temperature Sensor Malfunction

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Signal	DTC 2	DTC 2	DTC 2	--
Low Reference	--	DTC 2	DTC 2	--

The HVAC control monitors the ambient air temperature sensor with a low reference circuit and 5 V signal circuit. The HVAC control monitors the voltage drop across the sensor, which is proportional to temperature. When the ambient air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the ambient air temperatures are hot, the resistance of the sensors is 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 detects the sensor signal circuit is less than -40°C (-40°F).

•	The HVAC control detects the sensor signal circuit is more than 120°C (248°F).

Action Taken When the DTC Sets

•	The system operates using a default value.

•	The DTC will flash on the HVAC control display.

Conditions for Clearing the DTC

•	DTC will be cleared when restarting the engine.

•	DTC will be cleared when pushing the AUTO switch.

•	DTC will be cleared when rotating the fan control knob to 0.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Circuit/System Testing

Ignition OFF, disconnect the harness connector at the B9 Ambient Air Temperature Sensor.
Test for less than 10 Ω 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.

Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and the low reference circuit terminal B.

⇒	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.

⇒	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.

If all circuits test normal, replace the B9 Ambient Air Temperature Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Ambient Air Temperature Sensor Replacement

•	Heater and Air Conditioning Control Replacement