Circuit Description
The HVAC control assembly determines the outside air temperature through an input from the ambient air temperature sensor. The HVAC control assembly receives a voltage signal from the ambient air temperature sensor through circuit 735 . The ambient air temperature sensor is grounded by the HVAC control assembly through circuit 61.
The internal resistance of the ambient air temperature sensor decreases as temperature increases. The difference between the ambient air temperature sensor and the inside air temperature sensor measurements is displayed on the HVAC control assembly display.
Conditions for Setting the DTC
The HVAC control assembly performs a check on the operation of the ambient air temperature sensor and detects an open in circuit 735
Action Taken When the DTC Sets
| • | The HVAC control assembly stores DTC B0333 in memory. |
| • | The HVAC control assembly uses 9°C (49°F) as a substitute for the ambient air temperature reading , allowing the A/C system to continue operation. |
Conditions for Clearing the DTC
| • | An open in circuit 735 is no longer present. |
| • | Under all fault conditions, the ignition switch must be cycled from on to off, back to on before this DTC can change from current to history. |
| • | A history DTC clears after 100 drive cycles if a short to ground in circuit 735 is no longer present. |
| • | Using a scan tool. |
Diagnostic Aids
The following conditions may cause this DTC to set:
| • | A poor connection or open in circuit 735. |
| • | A poor connection or open in circuit 61. |
| • | A faulty ambient air temperature sensor. |
| • | A faulty HVAC control assembly . |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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This step checks for proper voltage value at the ambient air temperature sensor.
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This step determines whether circuit 61 or circuit 735 is open.
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This step checks for an open in circuit 61 .
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This step checks for an open in circuit 735.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the HVAC functional check preformed? | -- | Go to Step 2 | Go to Functional Check |
Is the measured voltage within the specified range? | 4.5-5.5V | Go to Step 6 | Go to Step 3 | |
Use a DMM to measure the voltage between the ambient air temperature sensor harness connector terminal A and ground. Is the measured voltage within the specified range? | 4.5-5.5V | Go to Step 4 | Go to Step 5 | |
Is the measured resistance within the specified range? | Less than 2ohms | Go to Step 8 | Go to Step 7 | |
Is the measured resistance within the specified range? | Less than 2ohms | Go to Step 8 | Go to Step 9 | |
6 | Check the ambient air temperature sensor connector terminals for poor connection. If OK, replace the ambient air temperature sensor if the connector is OK. Refer to Ambient Temperature Sensor Replacement . Is the repair complete? | -- | Go to Functional Check | -- |
7 | Locate and repair a poor connection or an open in circuit 61. Is the repair complete? | -- | Go to Functional Check | -- |
8 | Check the HVAC control assembly connector terminals for poor connection. IF OK, replace the HVAC control assembly. Refer to Control Assembly Replacement . Is the repair complete? | -- | Go to Functional Check | -- |
9 | Repair a poor connection or an open in circuit 735. Is the repair complete? | -- | Go to Functional Check | -- |
