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.
After a calibration or recalibration procedure is performed, the HVAC control module calculates the mode actuator travel range. The HVAC control module commands the actuator through it's full range. The HVAC control module stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum and maximum position values. Then the HVAC control module compares the travel range, minimum and maximum values to calibrated value ranges. If the travel range value is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful. The HVAC control module continuously compares the actual actuator position to the calibrated minimum and maximum position values.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
| • | The HVAC control module keep alive memory battery power must be interrupted to run the range check (recalibration procedure). |
Conditions for Setting the DTC
| • | Mode actuator position signal is less than 5 counts. |
| • | Mode actuator position signal is more than 250 counts. |
| • | The recirculation actuators total travel range (min-max) is less than or greater than the calibrated limits. |
Action Taken When the DTC Sets
| • | The DTC is stored in DTC information. |
| • | The HVAC control module will continue to make use of whatever travel range is still available. |
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 damaged or broken mode door and or actuator can cause this DTC to set. |
| • | The range fault can only be detected following a check of the actuator travel range. The actuator travel range check (recalibration procedure) can only be initiated by disrupting power to the HVAC control module. |
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Air Delivery/Temperature Control Schematics | ||||||||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check | ||||||
2 |
Does the result of the calculation indicate that the actual travel of the mode actuator is within the specified range? | 20-140 counts | Go to Step 3 | Go to Step 8 | ||||||
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 ground 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 a short to ground. 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 position signal 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 this test.
Does the drive shaft of the mode actuator rotate and do the counts change? | -- | Go to Step 10 | 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 13 | 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 | Replace the mode actuator. Refer to Mode Actuator Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
12 |
Important: Perform the travel range check (recalibration procedure) for the HVAC control module. Replace the HVAC control module. Refer to Control Assembly Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
