Circuit Description
The HVAC control module (IPM) monitors air temperature through air temperature sensors. 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 IPM requests A/C compressor clutch engagement and controls the appropriate air temperature actuator door positions in order to maintain the selected air temperature on the IPM. The ambient air temperature is displayed on the HVAC control module (IPM). The inside air temperature assembly contains an electric fan which pulls the air from the passenger compartment to the air temperature sensor.
| • | Output air temperature sensor 1 refers to the upper left air temperature sensor |
| • | Output air temperature sensor 2 refers to the lower left air temperature sensor |
| • | Output air temperature sensor 3 refers to the upper right air temperature sensor |
| • | Output air temperature sensor 4 refers to the lower right air temperature sensor |
| • | Output air temperature sensor 5 refers to the auxiliary air temperature sensor |
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B0159 Outside Air Temperature Sensor Circuit |
| • | DTC B0164 Passenger Compartment Temperature Sensor Circuit |
| • | DTC B0174 Output Air Temperature Sensor 1 |
| • | DTC B0179 Output Air Temperature Sensor 2 |
| • | DTC B0510 Output Air Temperature Sensor 3 |
| • | DTC B0515 Output Air Temperature Sensor 4 |
| • | DTC B0520 Output Air Temperature Sensor 5 |
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The IPM detects the signal circuit is less than 5 counts (0.09 V) or greater than 250 counts (4.90 V).
Action Taken When the DTC Sets
A default value will be used for the sensor data by the IPM. The scan tool displays the default sensor value in the Instrument Panel Module HVAC Sensors data list. The scan tool displays the actual sensor value in the Instrument Panel Module Open/Short data list.
Conditions for Clearing the DTC
| • | The DTC will become history if the IPM 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 the condition is 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.
-
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 | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the scan tool indicate that the sensor parameter is within the specified range? | 5-250 counts (0.09-4.90 V) | Go to Diagnostic Aids | Go to Step 3 |
Does the scan tool indicate that the sensor parameter is greater than the specified value? | 250 counts (4.90 V) | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the sensor parameter is less than the specified value? | 5 counts (0.09 V) | Go to Step 8 | Go to Step 6 | |
5 | Test the signal circuit of the appropriate 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 signal circuit of the appropriate 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 of the appropriate air temperature sensor 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 appropriate 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 instrument panel module (IPM). 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 appropriate air temperature sensor. Refer to the following: Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
