Circuit Description
The body control module (BCM) monitors the ambient air temperature sensor to display outside air temperature. The sensor signal is read by the BCM, scaled appropriately and transmitted to the HVAC control module through the GM LAN Low Speed bus. The temperature sensor is a 2-wire negative temperature co-efficient thermistor. The BCM applies 5 volts to an internal input resistor that is connected to the signal circuits of the ambient air temperature sensor. The BCM provides the ground to the ambient air temperature sensor through the low reference circuit. The BCM monitors the voltage drop across the ambient air temperature sensor and uses the input for automatic control calculations. When the ambient air temperatures are cold, the resistance of the sensors are high and the voltage signals are high. When the air temperatures are hot, the resistance of the sensors are low and the voltage signals are low. The BCM converts the voltage value to a temperature value of Celsius and Fahrenheit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B0158 Outside Air Temperature Sensor
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.
DTC Symptom | DTC Symptom Descriptor |
|---|---|
05 | Short to Battery or Open |
06 | Short to Ground or Open |
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The BCM detects the sensor signal circuit is less than 9°C (48°F) or more than -40°C (-40°F).
Conditions Taken When the DTC Sets
| • | The default value of 3°C (38°F) will be substituted for the ambient air temperature sensor data by the BCM. The Ambient Air Temp displayed on the scan tool, 16°C (60°F) in the HVAC sensor data list, will be the default value. |
| • | The DIC will display the set temperature when ON. |
Conditions for Clearing the DTC
| • | The DTC will become history if the BCM no longer detects a failure. |
| • | The history DTC will clear after 40 fault-free ignition cycles. |
| • | The DTC can be cleared by using a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The operating range of the sensor is between -40 to +88°C (-40 to +190°F). If the scan tool displays a value between 0-9°C (48°F) or -40°C (-40°F), then the sensor is performing outside of its designed limits.
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This step tests for the proper operation of the circuit in the high voltage range.
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This step 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.
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Test the signal circuit for a short to ground.
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This step tests the signal circuit for a short to voltage, a high resistance, or an open.
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This step tests the low reference circuit for a high resistance or an open.
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 |
Does the scan tool indicate that the temperature sensor parameter is within the specified range? | -40 to +88°C (-40 to +190°F) | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Does the scan tool indicate that the temperature sensor parameter is more than the specified value? | -40°C (-40°F) | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the temperature sensor parameter is less than the specified value? | 9°C (48°F) | Go to Step 8 | Go to Step 6 | |
Test the signal circuit of the ambient 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 | |
Test the signal circuit of the ambient 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 | |
Test the low reference circuit of the ambient 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 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 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the body control module (BCM). 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 ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement in Stationary Windows. Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the BCM. 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 |
