Circuit Description
The mode actuator is an electronic device that incorporates a stepper motor and a feedback potentiometer. The HVAC control module determines the position of the mode actuator that is based on the voltage from the potentiometer. When the keep alive RAM memory, the battery positive voltage circuit, of the HVAC control module is interrupted, the module will calibrate the actuators. The HVAC control module performs a travel range comparison of the determined values of the actuator to the calibrated values within the HVAC control module. If the determined range does not equal the calibrated expected range, the actuator will be considered not calibrated, and the DTC will set. The HVAC control module will also perform a continuous test on the current feedback value. If the feedback value does not fall within the calibrated range, the DTC will set.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
| • | The battery positive voltage circuit, which provides keep alive RAM memory power, of the HVAC control module must be interrupted in order to run the recalibration. This includes disconnecting the battery, removal of the Radio fuse and disconnecting the HVAC control module. |
Conditions for Setting the DTC
| • | The position signal of the mode door is out of the range 0.09-4.0 volts (5-250 counts). |
| • | The total travel range of the mode actuator falls without the calibrated limits. |
Action Taken When the DTC Sets
| • | The HVAC control module will continue to make use of whatever travel range is still available. |
| • | Each time the ignition switch is turned ON, the HVAC control module retests the actuator travel range. |
Conditions for Clearing the DTC
| • | If the HVAC control no longer detects a condition, then the DTC will become history. |
| • | The history DTC will clear after 50 ignition cycles without a condition. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
| • | The range fault can only be detected following a recalibration. The recalibration can only be initiated by removing the battery positive voltage circuit to the HVAC control module. |
| • | The calibration limit is 64-216 counts. An actual range below this limit suggests an obstruction, something stuck in the door which limits travel. An actual range above this limit suggests an excessive travel condition, damaged, or missing foam seals. |
| • | A damaged mode door or a damaged actuator can cause this DTC to set. |
| • | An intermittent short to ground on the HVAC class 2 serial data circuit can set this DTC. Recalibrate actuators and test system. |
| • | If the condition is not present, refer to Testing for Intermittent and Poor Connectionsin Wiring Systems. |
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 result of the calculation indicate that the actual travel of the mode actuator is within the specified range? | 64-216 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 |
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 | ||||||
