Circuit Description
The HVAC control module receives a left air temperature actuator position signal from the left air temperature actuator. The left air temperature actuator position sensor is a potentiometer that is tied to a 5 volt reference source. The variable output from the potentiometer feeds back a position signal to a pull-up resistor located in the HVAC control module. This signal is used to determine the necessary drive signal to the left air temperature 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 module.
Condition for Running DTC
The ignition is in the ON position.
Conditions for Setting the DTC
Left air temperature actuator signal circuit stays at 4.5 volts or higher.
Action Taken When the DTC Sets
No driver warning message will be displayed for this DTC.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a failure. |
| • | The history DTC will clear after 50 fault free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
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 left air temperature actuator with the scan tool from fully open to fully closed. Monitor the LH MIX MTR POSITION FEE 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.
If condition not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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This step checks for a default action by the actuator. The actuator will default to 128 counts if the air temperature door position circuit is open, shorted to ground, or shorted to voltage. It will also default to this value if the low reference circuit or the 5 volt reference circuit is open.
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Tests for the proper operation of the circuit in the high voltage range.
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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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Tests for a short to ground in the 5 volt reference circuit.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||||||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |||||||
2 |
Does the scan tool indicate that the LH Mix Mtr Position Fee parameter is within the specified range? | 1-3 Counts | Go to Step 9 | Go to Step 3 | ||||||
Does the scan tool indicate that the LH Mix Mtr Position Fee parameter is near the specified value? | 128 Counts | Go to Step 5 | Go to Step 4 | |||||||
Does the scan tool indicate that the LH Mix Mtr Position Fee parameter is within the specified range? | 3-252 Counts | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 5 | |||||||
Test the ground circuit of the left air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 6 | |||||||
Test the 5 volt reference circuit of the left air temperature actuator for a short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 7 | |||||||
7 | Test the air temperature door position signal circuit of left air temperature actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 8 | ||||||
8 |
Important: : The air temperature actuator connector and the HVAC control module connector must be connected to correctly perform the test.
Does the left air temperature actuator drive shaft rotate and do the counts change? | -- | Go to Step 13 | Go to Step 9 | ||||||
9 | Inspect the air temperature door and the left air temperature actuator for the following:
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||
10 | Inspect for poor connections at the harness connector of the left air temperature actuator. 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 13 | Go to Step 12 | ||||||
11 | Inspect for poor connections at the harness connector of 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 13 | Go to Step 12 | ||||||
12 |
Important:: Perform the recalibration for the air temperature actuator. Replace the left air temperature actuator. Refer to Air Temperature Actuator Replacement - Left Side Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
