Circuit Description
The HVAC control module monitors the outside ambient air temperature via an ambient air temperature sensor. When the air is cold, the sensor resistance voltage and the signal voltage are high. When the air is warm, the sensor resistance voltage and the signal voltage are low.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects that the signal circuit is out of the range 0.09-5.0 volts.
Action Taken When the DTC Sets
A default value will be used for the sensor data by the HVAC control module. The sensor reading, which displays on the scan tool in the HVAC data list, will be the default value.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a condition. |
| • | The history DTC clears after 50 fault free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The number below refers to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference : HVAC Schematics | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
Does the voltage measure near the specified value? | 5 V | Go to Step 3 | Go to Step 4 | |
3 | Measure the voltage from the signal circuit to the low reference circuit of the ambient air temperature sensor. Does the voltage measure near the specified value? | 5 V | Go to Step 6 | Go to Step 5 |
4 | Test the signal circuit of the ambient air temperature sensor for a short to voltage, short to ground a high resistance, or an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
5 | Test the low reference circuit of the ambient air temperature sensor for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
6 | Inspect for poor connections at the harness connector of the ambient air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 |
7 | Test the resistance of the ambient air temperature sensor. Refer to Sensor Resistance Table . Is the resistance measurement near the Sensor Resistance Table value? | -- | Go to Step 8 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
9 | Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 |
Important: Perform the calibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the DTC set again? | -- | Go to Step 2 | -- |
