Circuit Description
The HVAC control module monitors the ambient air temperature through an ambient air temperature sensor. The ambient air temperature sensor is a variable resistor. The HVAC control module supplies 5 volts to the ambient air temperature sensor signal circuit, and provides a low reference circuit. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The HVAC control module displays the outside air temperature on the HVAC control module.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects the signal circuit is more than 4.90 V.
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 with a scan tool. |
Diagnostic Aids
If condition not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The operating range of the sensor is between 0.09-4.90 volts. If the scan tool displays a value between 0-.08 volt or 4.91-5.0 volts, then the sensor is performing outside of its designed limits.
-
Tests for the proper operation of the circuit in the high voltage range.
-
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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
Does the scan tool indicate that the Outside Temp Sensor parameter is within the specified range? | 0.09-4.90 V | Go to Diagnostic Aids | Go to Step 3 | |
Does the scan tool indicate that the Outside Temp Sensor parameter is greater than the specified value? | 4.90 V | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the Outside Temp Sensor parameter is less than the specified value? | 0.09 V | Go to Step 8 | Go to Step 6 | |
5 | Test the ambient air temperature sensor signal circuit of the ambient air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
6 | Test the ambient air temperature sensor signal circuit of the ambient air temperature sensor for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 |
7 | Test the low reference circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the ambient air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
