Circuit Description
The heater-A/C control determines the inside air temperature through an input from the inside air temperature sensor. The heater-A/C control receives a voltage signal from the inside air temperature sensor through circuit 734 (DK GRN). The inside air temperature sensor is grounded by the heater-A/C control through circuit 61 (YEL).
The internal resistance of the inside air temperature sensor decreases as the 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 in order 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.
Conditions for Setting the DTC
The heater-A/C control performs a check on the operation of the inside air temperature sensor and detects a short to ground in circuit 734 (DK GRN).
Action Taken When the DTC Sets
| • | The heater-A/C control stores DTC B0337 in memory. |
| • | The heater-A/C control uses 24°C (75°F) as a substitute for the inside air temperature reading , allowing the A/C system to continue operation. |
Conditions for Clearing the DTC
| • | A short to ground in circuit 734 (DK GRN) 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 734 (DK GRN) is no longer present. |
| • | Using a scan tool |
Diagnostic Aids
The following conditions may cause this DTC to set:
| • | A short to ground in circuit 734 (DK GRN) |
| • | A voltage spike in circuit 734 (DK GRN) |
| • | A faulty inside 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.
-
This step checks for proper voltage value at the inside air temperature sensor.
-
This step checks for a short to ground in 734 (DK GRN) .
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 value? | 4.5-5.5V | Go to Step 3 | Go to Step 4 | |
3 |
Is the repair complete? | -- | Go to Step 7 | -- |
Is the measured resistance same as the specified value? | ∞ | Go to Step 6 | Go to Step 5 | |
5 | Locate and repair a short to ground in circuit 734 (DK GRN). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 7 | -- |
6 | Replace the heater-A/C control. Refer to Control Assembly Replacement . Is the repair complete? | -- | Go to Step 7 | -- |
7 | Verify the operation of the system. Does the system operate properly? | -- | System OK | Go to Diagnostic System Check |
