Circuit Description
The rear junction block supplies ignition voltage through circuit 141 (BRN). The HCM commands the actuator to move by suppling voltage on the command line circuit 1614 (DK GRN). The command line voltage and motor actions are as follows:
| • | 0 volts moves toward full hot. |
| • | 2.5 volts stops the motor. |
| • | 5 volts moves toward full cold. |
The HCM determines the current position by monitoring the voltage on the feedback circuit 1838 (PPL). A feedback potentiometer supplies a regulated 5 volt signal by the HCM on circuit 705 (GRY), and a ground from the HCM circuit 1791 (YEL). The pot is gear driven inside the actuator. The feedback voltage is a function of the motor position with a high voltage of 4-5 volts indicating full cold door position. A low voltage of less then 1 volt indicates the full hot position. Operation of the air mix door actuator can be evaluated through scan tool data.
The air inlet door motor is an electronic actuator stepper motor with a feedback potentiometer. The heater and A/C programmer determines the position of the door motor based on the voltage from the potentiometer. When the airflow is being recirculated, the voltage is low. When outside air is being admitted, voltage is high. The heater and A/C programmer controls the air inlet door motor to position the air inlet door in either the recirc or the fresh air positions as selected by the vehicle occupants.
Conditions for Setting the DTC
| • | Ignition is ON. |
| • | The heater and A/C programmer detects the signal circuit is less than 0.61 volts, (31 counts) or greater than 3.94 volts, (201 counts). |
Action Taken When the DTC Sets
| • | A default value of 0.78 volts, (40 counts) will be used for the sensor data by the heater and A/C programmer. |
| • | The air inlet door will be set to the outside air position. |
Conditions for Clearing the DTC
| • | The DTC can be cleared with a scan tool. |
| • | A history DTC will clear after 50 fault free ignition cycles. |
| • | The DTC will become history if the heater and A/C programmer no longer detects a failure. |
Diagnostic Aids
| • | A disconnected or broken door may also set this DTC by allowing the actuator to travel to its internal stops (overtravel condition). |
| • | Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Perform the HVAC Diagnostic Symptom Check before continuing with the diagnosis of this DTC.
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This step checks the working parameters of the Air Inlet Door through the scan tool.
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Determines if the motor ground circuit of the air inlet actuator has high resistance or an open and fixes it.
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Determines if the heater and A/C programmer connector has an intermittent or poor connection and fixes it.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the HVAC diagnostic system check performed? | -- | Go to Step 2 | Go to Diagnostic System Check | |
Does the scan tool indicate that the Air Inlet Door Actual parameter is within the specified range? | 0.61 - 3.94 V | Go to Diagnostic Aids | Go to Step 3 | |
3 |
Does the scan tool indicate that the Air Inlet Door Actual parameter changes when the Air Inlet Door is commanded from Outside to Recirc? | -- | Go to Step 12 | Go to Step 4 |
4 |
Does the scan tool indicate that the Air Inlet Door actual parameter is greater than the specified value? | 3.94 V | Go to Step 5 | Go to Step 9 |
5 |
Does the scan tool indicate that the Air Inlet Door actual parameter is less than the specified value? | 0.61 V | Go to Step 6 | Go to Step 10 |
6 |
Does the scan tool indicate that the Air Inlet Door actual parameter is greater than the specified value? | 3. 94 V | Go to Step 8 | Go to Step 7 |
7 | Test the 5 volt reference circuit of the air inlet door position sensor for a short to ground. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
8 | Test the 5 volt reference circuit of the air inlet door position sensor for a short to voltage, a high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 13 |
9 | Test the signal circuit of the air inlet door position sensor for a short to ground. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
10 | Test the signal circuit of the air inlet door position sensor for a short to voltage, a high resistance, or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 11 |
Test the motor ground circuit of the air inlet actuator for a high resistance or an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | |
12 | Inspect the air inlet door for a condition allowing excessive travel of the actuator. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 13 |
13 | Inspect for poor connections at the harness connector of the air inlet actuator. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
Inspect for poor connections at the harness connector of the heater and A/C programmer. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | |
15 | Replace the air inlet actuator. Refer to Air Inlet Actuator Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
16 | Replace the heater and A/C programmer. Refer to Programmer Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the DTC reset? | -- | Go to Step 2 | -- |
