Circuit Description
The mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The HVAC control module controls the mode door position by sending a control signal to the actuator. The signal's value is dependent upon the desired mode selected by the vehicle occupants. As the actuator moves, the potentiometer produces the actual door position signal that is sent to the HVAC control module. The HVAC control module continues to command the actuator to move until the desired and actual values are equal. The door directs airflow through the outlets as selected by the vehicles occupants.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
| • | An mode actuator positional change is attempted. |
Conditions for Setting the DTC
The actual mode door position differs from the commanded mode door position by 4 counts or more.
Action Taken When the DTC Sets
The mode actuator is considered stalled and the HVAC control module will command the mode actuator to stop rotation (2.5 V).
Conditions for Clearing the DTC
| • | If the HVAC control no longer detects a failure, then the DTC will become history. |
| • | The history DTC will clear after 50 ignition cycles without a failure. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
| • | A dead zone exists in a range 10 counts above or below the mode door max or mode door min positions. When the mode door actual data parameter is within the dead zone, the DTC will not set. If the mode door commanded data parameter differs from the mode door actual data parameter by 4 counts or more outside the dead zone, the DTC will set. |
| • | A damaged or broken mode door and or actuator can cause this DTC to set. |
Step | Action | Values | 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 Mode Door Commanded data parameter is within the specified value of the Mode Door Actual data parameter? | 0-3 counts | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | ||||||
3 |
Does the scan tool indicate that the mode actuator actual parameter changes within the specified range when it is commanded from panel to defrost? | 5-250 counts | Go to Diagnostic Aids | Go to Step 4 | ||||||
4 | Test the mode door actuator ignition 3 circuit 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 5 | ||||||
5 | Test the 5 volt reference circuit of the mode 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 | ||||||
6 | Test the mode door control circuit for an open, 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 |
Important: The mode actuator connector and the HVAC control module connector must be connected to correctly perform test.
Does the mode actuator drive shaft rotate and do the counts change? | -- | Go to Step 13 | Go to Step 8 | ||||||
8 | Inspect the mode door and the mode actuator for the following:
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||
9 | Inspect for poor connections at the harness connector of the mode 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 11 | ||||||
10 | Inspect for poor connections at the harness connector of the 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 | ||||||
11 |
Important: Perform the recalibration procedure for the mode actuator. Replace the mode actuator. Refer to Mode Actuator Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
12 |
Important: Perform the recalibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
