B0337

CIRCUIT DESCRIPTION
The following DTCs are for the temperature sensors monitored by the HVAC control module:
- B0332 - ambient air temperature sensor
- B0333 - ambient air temperature sensor
- B0337 - inside air temperature sensor
- B0338 - inside air temperature sensor

The HVAC control module monitors the temperature sensors to maintain the comfort level inside of the vehicle. The temperature sensors are a 2 wire negative temperature co-efficient thermistor. The HVAC control module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The HVAC control module provides the ground to the air temperature sensors through the low reference circuit. The HVAC control module monitors the voltage drop across the air temperature sensors and uses the inputs for automatic control calculations. When the air temperatures are cold, the resistance of the sensors are high and the voltage signals are high. When the air temperatures are hot, the resistance of the sensors are low and the voltage signals are low. The HVAC control module converts the voltage values to count values where 1 V is approximately equal to 51 counts.

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 0.09 volt (5 counts) or more than 4.90 volts (250 counts).

ACTION TAKEN WHEN THE DTC SETS
- The HVAC control module uses a default value.
- The HVAC control module will display - - for ambient air temperature when OFF.

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 50 fault-free ignition cycles.
- The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
If the condition is not present, Diagnostic Aids for circuit testing and wiring repair procedure.

TEST DESCRIPTION

Steps 1-3:

Steps 4-8:

Steps 9-12:

The numbers below refer to the step numbers on the diagnostic table.
2. The operating range of the sensor is between 0.09-4.90 volts. If the scan tool displays a value between 0-0.08 volt or 4.91-5.0 volts, then the sensor is performing outside of its designed limits.
3. Tests for the proper operation of the circuit in the high voltage range.
4. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
5. Tests the signal circuit for a short to ground.
6. Test the signal circuit for a short to voltage, a high resistance, or an open.
7. Tests the low reference circuit for a high resistance or an open.