Circuit Description
The powertrain control module (PCM) uses the rationality diagnostic to determine if the sensor is skewed to a higher temperature range that would reduce the amount of time that would otherwise be spent with the engine off at idle. The PCM uses the intake air temperature (IAT) sensor input and the ambient air temperature sensor input from the HVAC control module to calculate the approximate ambient air temperature.
The HVAC control also monitors the ambient air temperature sensor and sends the data to the hybrid control module (HCM). The PCM monitors the intake air temperature sensor and sends the data to the HCM. The HCM uses these two data parameters to determine if the ambient air temperature sensor may not be with in range. If the HCM determines that the IAT sensor is 10°C (18°F) greater than the ambient air temperature sensor input, then DTC B0159 will set.
Conditions for Running the DTC
| • | The following DTCs are not set as current in the PCM: |
| - | P0112 |
| - | P0113 |
| - | P0502 |
| - | P0503 |
| - | P2610 |
| • | The IAT input is not less than -7°C (19°F). |
| • | DTC B0159 is not set in the HVAC control module. |
| • | No loss of communication with the HVAC control module. |
| • | The ignition has been in the OFF position for 10 hours |
Conditions for Setting the DTC
The IAT input is 10°C (18°F) greater than the ambient air temperature input for 1 second. The diagnostic is run 1 time during each ignition cycle.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
| • | If DTC is set in the HVAC control module, perform that diagnostic first. Refer to DTC B0159 or B0164 in HVAC Systems - Automatic. |
| • | If condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views | ||||
1 | Did you perform the Engine Cooling Diagnostic System Check? | -- | Go to Step 2 | |
Does the scan tool indicate that B0159 is a current DTC? | -- | Go to Step 3 | Go to Diagnostic Aids | |
3 |
Does the voltage measure near the specified value? | 5 V | Go to Step 4 | Go to Step 5 |
4 | Measure the voltage from the signal circuit to the low reference circuit of the ambient air temperature sensor. Does the voltage measure near the specified value? | 5 V | Go to Step 7 | Go to Step 6 |
5 | Test the signal circuit of the ambient air temperature sensor for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
6 | Test the low reference circuit of the ambient air temperature sensor for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
7 | Inspect for poor connections at the harness connector of the ambient 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 11 | Go to Step 9 |
8 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
9 | Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement in HVAC Systems - Automatic. Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the HVAC control module. Refer to HVAC Control Module Replacement in HVAC Systems - Automatic. Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
