Circuit Description
The mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The instrument panel integration module (IPM) 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. The control signal is near 0 V when the mode actuator is commanded toward the defrost position, near 5 V when commanded toward the vent position, and near 2.5 V when stationary. As the mode actuator moves, the potentiometer produces the actual door position signal that is sent to the IPM. The IPM continues to command the actuator to move until the desired and actual values are equal.
When a calibration or recalibration procedure is performed, the IPM calculates the mode door travel range. The IPM commands the actuator through it's full range. The IPM stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum position value from the maximum position value. The IPM compares the travel range to calibrated limits. 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 IPM continuously compares the actual actuator position to the calibrated minimum and maximum position values.
Conditions for Running the DTC
| • | The IPM power is interrupted. |
| • | The range fault code can only be set following a calibration/recalibration of the mode actuator. |
| • | The IPM will not perform a calibration/recalibration of the mode actuator if DTC B0252 is set as current. |
Conditions for Setting the DTC
The actual total travel range of the mode door (max - min) is less than 200 counts or greater than 246 counts.
Action Taken When the DTC Sets
| • | The IPM will continue to make use of whatever travel range is still available. |
| • | The IPM will recalibrate the mode door travel range each time the ignition switch is turned ON. |
Conditions for Clearing the DTC
| • | A successful recalibration of the mode door must be completed. |
| • | A history DTC clears after 50 malfunction free ignition cycles. |
| • | The IPM receives the clear code command from the scan tool. |
Diagnostic Aids
The calibration limit is 200 to 246 counts (3.9-4.8 V). An actual range below this limit suggests an obstruction of the mode door or a binding linkage limiting travel. An actual range above this limit suggests an over travel condition (damaged or missing foam seals). If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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 travel range of the mode door is within the specified range? | 200-246 Counts (3.9-4.8 V) | Go to Diagnostic Aids | Go to Step 3 | ||||||||
Does the result of the calculation indicate that the travel range of the mode door is greater than the specified value? | 15 Counts (0.3 V) | Go to Step 10 | Go to Step 4 | |||||||||
4 |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 13 | ||||||||
5 | Measure the voltage from the 5 volt reference circuit of the mode actuator to a good ground. Does the voltage measure near the specified value? | 5 V | Go to Step 6 | Go to Step 9 | ||||||||
6 |
Important: The ignition must be cycled from OFF to ON with the mode actuator disconnected during this step. Failure to do this may result in misdiagnosis.
Does the voltage measure near the specified value? | 2.3-2.7 V | Go to Step 8 | Go to Step 7 | ||||||||
7 | Test the mode door control circuit of the mode actuator 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 16 | Go to Step 12 | ||||||||
|
Important: Ensure that the mode actuator control module and the instrument panel integration module control assembly are connected during this step in order to avoid misdiagnosis.
Does the scan tool indicate that the total travel range of the mode door is greater than the specified value? | 15 Counts | Go to Step 12 | Go to Step 10 | |||||||||
9 | 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 16 | Go to Step 12 | ||||||||
10 | Inspect the mode door and the mode actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 11 | ||||||||
11 | 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 16 | Go to Step 14 | ||||||||
12 | Inspect for poor connections at the harness connector of the instrument panel integration module (IPM). 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 16 | Go to Step 15 | ||||||||
13 | Repair the ignition 3 voltage circuit of the mode actuator. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 16 | -- | ||||||||
14 |
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 16 | -- | ||||||||
15 |
Important: Perform the recalibration procedure for the instrument panel integration module (IPM) Replace the instrument panel integration module (IPM). Refer to Instrument Panel Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||
16 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||||
