Circuit Description
The heater-A/C control determines the outside air temperature through an input from the ambient air temperature sensor. The heater-A/C control receives a voltage signal from the ambient air temperature sensor through circuit 735 (Lt GRN/BLK). The ambient air temperature sensor is grounded by the heater-A/C control through circuit 61 (YEL).
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 used by the heater-A/C control to determine whether the incoming air should be cooled or warmed, and to what degree, in order to bring the inside air temperature to the selected temperature as quickly as possible. This is accomplished through operation of the control solenoids. The heater-A/C control also uses the signal from the ambient air temperature sensor to display the outside air temperature on the heater-A/C control display.
Conditions for Setting the DTC
The heater-A/C control performs a check on the operation of the ambient air temperature sensor and detects an open in circuit 735 (Lt GRN/BLK).
Action Taken When the DTC Sets
| • | The heater-A/C control stores DTC B0333 in memory. |
| • | The heater-A/C control 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 (Lt GRN/BLK) 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 (Lt GRN/BLK) 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 (Lt GRN/BLK). |
| • | A poor connection or open in circuit 61(YEL). |
| • | A faulty ambient air temperature sensor. |
| • | A faulty heater-A/C control. |
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 (YEL) or circuit 735 (LT GRN/BLK) is open.
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This step checks for an open in circuit 61(YEL) .
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This step checks for an open in circuit 735 (LT GRN/BLK).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the heater-A/C control diagnostic system check performed? | -- | Go to Step 2 | Go to Diagnostic System 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 less than the specified value? | 2ohms | Go to Step 8 | Go to Step 7 | |
Is the measured resistance less than the specified value? | 2ohms | Go to Step 8 | Go to Step 9 | |
6 | Check the ambient air temperature sensor connector terminals for poor contact and repair as needed. Replace the ambient air temperature sensor if the connector is OK. Refer to Ambient Temperature Sensor Replacement . Is the repair complete? | -- | System OK | -- |
7 | Locate and repair a poor connection or an open in circuit 61(YEL). Is the repair complete? | -- | System OK | -- |
8 | Check the heater-A/C control connector terminals for poor contact and repair as needed. Replace the heater-A/C control if the connector is OK . Refer to Control Assembly Replacement . Is the repair complete? | -- | System OK | -- |
9 | Locate and repair a poor connection or an open in circuit 735 (LT GRN/BLK). Is the repair complete? | -- | System OK | -- |
