Circuit Description
The HVAC control head receives a LH electric actuator position signal from the LH electric actuator. The LH electric actuator position sensor is a potentiometer that is tied to a 5 volt reference source through CKT 1791 and to ground through CKT 1798, both from the HVAC control head. The variable output from the potentiometer feeds back a position signal through CKT 733 to a pull-up resistor located in the HVAC control head. This signal is used to determine the necessary drive signal to the LH electric actuator motor to provide the proper air mix door position. This value is stored in the Keep Alive Memory (KAM) portion of the HVAC control head.
Conditions for Setting the DTC
| • | With the ignition in the ON position, CKT 733 is checked continuously. |
| • | CKT 733 stays at or near 0 volts. |
Action Taken When the DTC Sets
| • | The HVAC control head stores a DTC B0361 in memory. |
| • | No driver warning message will be displayed for this DTC. |
Conditions for Clearing the DTC
| • | Using the IPC clearing feature. |
| • | Using a scan tool. |
| • | A history DTC will clear after 50 consecutive ignition cycles if the conditions for the fault is no longer present. |
Diagnostic Aids
| • | If the DTC is a history or an intermittent. Try to perform the tests shown while "wiggling" wiring and connectors, this can often cause the malfunction to appear. |
| • | Visually inspect sensor connector and harness for damage, corrosion or water intrusion. |
| • | Check for adequate terminal tension, mis-routed harness, rubbed through wire insulation, and broken wire inside insulation. |
| • | Install a scan tool to the diagnostic link connector. Turn the ignition switch to the ON position. Select the OUTPUT CONTROL screen in HVAC special functions. Use the MISCELLANEOUS TEST screen to manually drive the LH electric actuator with the scan tool from fully open to fully closed. Monitor the LH MIX MTR POSITION FEEDBACK with the scan tool when this is done. A normal position feedback signal should range between 0-255 counts as the electric actuator is being moved. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
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This test checks for the 5 volt reference signal being sent from the HVAC control head along CKT 1791.
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This step is determining if a short to battery voltage exists on CKT 1791.
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This step is checking for the 5 volt reference signal being sent from the HVAC control head along CKT 733.
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This step is checking for a short to ground in CKT 733.
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This step will repair a short to ground in CKT 733.
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Replace the HVAC control head.
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This test checks for a short to ground in CKT 1791.
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Repair the short to ground in CKT 1791.
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This step is checking for continuity of CKT 1798.
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Repair open in CKT 1798.
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This step will replace the LH electric actuator.
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Erase all DTCs and recheck for repair verification.
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This step is determining if a short to battery voltage exists on CKT 1791 with the HVAC control head and the LH electric actuator disconnected.
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Checks for an open in CKT 1791.
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Repair the open in CKT 1791.
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Repair the short to battery voltage in CKT 1791.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Were you sent here from the HVAC System Check (CJ2)? | -- | Go to HVAC System Check (CJ2) | |
Is the voltage within the specified values? | 4.0-6.0V | |||
Is the measured voltage in step #2 greater than the specified value? | 6.0V | |||
Use a DMM to measure the voltage between terminal 9 of the LH electric actuator connector and ground. Is the voltage within the specified values? | 4.0-6.0V | |||
Is CKT 733 shorted to ground? | -- | |||
Locate and repair a short to ground in CKT 733. Is the repair complete? | -- | -- | ||
Replace the HVAC control head. Is the repair complete? | -- | -- | ||
Is CKT 1791 shorted to ground? | -- | |||
Locate and repair a short to ground in CKT 1791. Is the repair complete? | -- | -- | ||
Is CKT 1798 continuous between these connectors? | -- | |||
Locate and repair an open or high resistance in CKT 1798. Is the repair complete? | -- | -- | ||
Replace the LH Electric Actuator. Is the repair complete? | -- | -- | ||
Using a scan tool, clear all DTCs from memory. Do all DTCs erase from memory? | -- | Go to HVAC System Check (CJ2) | Refer to appropriate DTC table for diagnosis | |
Is the voltage greater then the specified value? | 6.0V | |||
Is the resistance between the HVAC control head connector terminal C10 and the LH electric actuator connector terminal 10 less than the specified values? | 0.5ohms | |||
Locate and repair an open or a high resistance in CKT 1791 between the LH electric actuator connector and the HVAC control head. Is the repair complete? | -- | -- | ||
Locate and repair a short to battery voltage in CKT 1791 between the LH electric actuator connector and the HVAC control head. Is the repair complete? | -- | -- |
