Circuit Description
The Inside Air Temperature Sensor is a ceramicist that controls signal voltage to the HVAC Control Module (ACME). The inside air temperature sensor system contains an aspirator which pulls the air from the passenger compartment through the sensor. The ACME supplies voltage on circuit 734. When the sensor is cold, the resistance is high and the ACME will sense a high signal voltage at terminal B.A. connector C. When the sensor warms, resistance is reduced and the signal voltage is pulled low through circuit 61. Signal voltage will vary from 5 V (open circuit) to 0 V (short circuit).
Conditions for Setting the DTC
| • | The ignition is ON. |
| • | DTC Bail is not set. |
| • | Circuit short or open. |
Action Taken When the DTC Sets
| • | A default value of HC (75°F) will be used by the HCM. |
| • | The default value allows the system to operate. |
Conditions for Clearing the DTC
| • | Using a Scan Tool . |
| • | A history DTC will clear after 50 fault free ignition cycles. |
| • | HCM battery voltage is interrupted. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Perform the Body Control Module (BCM) diagnostic system check before continuing with the diagnosis of this DTC.
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Ensures that the DTC was not set in error.
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Determines whether the cause of the malfunction is the sensor or an open or a short in a circuit.
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Determines if the IPM is malfunctioning.
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Clear all the DTC's after the repair procedures are complete.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Did you perform the BCM diagnostic system check? | -- | Go to Step 2 | ||
2 |
Refer to Measuring Voltage in Wiring Systems. Is the specified voltage measured? | 4.5-5.5 V | Go to Step 3 | Go to Step 7 |
Did the DTC reset? | -- | Go to Step 4 | ||
Did the inside air temperature sensor voltage decrease? | -- | Go to Step 6 | Go to Step 5 | |
Is the repair complete? | -- | Go to Step 13 | -- | |
6 | Replace the sensor. Refer to Inside Air Temperature Sensor Replacement . Is the replacement complete? | -- | Go to Step 13 | -- |
7 | Measure the voltage between sensor terminal A and ground. Refer to Measuring Voltage in Wiring Systems. Is the voltage within the specified range? | 4.5-5.5 V | Go to Step 8 | Go to Step 10 |
8 | Inspect HVAC sensor DTCs. Are all HVAC sensor DTCs present? | -- | Go to Step 9 | Go to Step 12 |
9 |
Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 13 | -- |
10 | Measure the voltage between HCM terminal B4 and ground. Refer to Measuring Voltage in Wiring Systems. Is the voltage within the specified range? | 4.5-5.5 V | Go to Step 11 | Go to Step 5 |
11 | Repair the open in CKT 734 (DK GRN). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 13 | -- |
12 | Repair the open in CKT 61 (YEL). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 13 | -- |
Is the A/C system operating normally? | -- | Go to Diagnostic System Check - Body Control System BCM Diagnostic System Check | -- |
