Circuit Description
Air temperature sensors allow the HVAC control module to monitor the discharge duct air , outside air and inside air temperatures. The HVAC control module provides ground to the air temperature sensor through the low reference circuit. The HVAC control module monitors the voltage drop across the air temperature sensor thermistor by supplying a 5 volt reference to the signal circuit of the air temperature sensor for automatic control calculations. When the air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the air temperatures are hot, the resistances of the sensors are low and the voltage signals are low. The HVAC control module can read voltage values and count values where 1 volt is approximately equal to 51 counts.
| • | Outside Air Temperature Sensor refers to the ambient air temperature sensor. |
| • | Passenger Compartment Temperature Sensor refers to the inside 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. |
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B0159 Outside Air Temperature Sensor Circuit Range/Performance |
| • | DTC B0164 Passenger Compartment Temperature Sensor Circuit Range/Performance |
| • | DTC B0174 Output Air Temperature Sensor 1 Circuit Range/Performance |
| • | DTC B0179 Output Air Temperature Sensor 2 Circuit Range/Performance |
| • | DTC B0510 Output Air Temperature Sensor 3 Circuit Range/Performance |
| • | DTC B0515 Output Air Temperature Sensor 4 Circuit Range/Performance |
Conditions for Running the DTC
| • | Battery voltage is within 8.7-16.5 volts. |
| • | The ignition is ON. |
Conditions for Setting the DTC
The HVAC control module determines that the value of the air temperature parameter is less than 5 counts or greater than 250 counts.
Action Taken When the DTC Sets
The air temperature sensors operate using a default value. The default values are not displayed on the scan tool.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a fault. |
| • | The history DTC will clear after 100 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Verifies that the temperature displayed is not within the calibrated range.
-
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 | Value(s) | 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 | |
Does the scan tool indicate that the Duct Actual parameter is within the specified range? | 5-250 Counts | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
Does the scan tool indicate that the Duct Actual data parameter is greater than the specified value? | 250 Counts | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the Duct Actual data parameter is less than the specified value? | 5 Counts | Go to Step 8 | Go to Step 6 | |
5 | Test the appropriate signal circuit of the air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs . 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 . 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 . 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 . 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 HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the air temperature sensor. Refer to the appropriate replacement procedure: Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the HVAC control module. Refer to Control Module References 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 |
