Circuit Description
The rear junction block supplies ignition voltage through circuit 141 (BRN). The IPM commands the actuator to move by suppling voltage on the command circuit 1236 (WHT/BLK). The command line voltage and motor actions are as follows:
| • | 0 volts moves toward full hot. |
| • | 2.5 volts stops the motor. |
| • | 5 volts moves toward full cold. |
The IPM determines the current position by monitoring the voltage on the feedback circuit 1646 (DK BLU). A feedback potentiometer supplies a regulated 5 volt signal by the IPM on circuit 705 (GRY), and a ground from the IPM circuit 1791 (YEL). The pot is gear driven inside the actuator. The feedback voltage is a function of the motor position with a high voltage of 4-5 volts indicating full cold door position. A low voltage of less then 1 volt indicates the full hot position. Operation of the air mix door actuator can be evaluated through scan tool data.
Conditions for Setting the DTC
| • | Ignition is ON. |
| • | Feedback circuit is open or shorted. |
Action Taken When the DTC Sets
| • | A default value of 128 counts will be used by the IPM. |
| • | This default value results in only two positions of the actuator full hot and full cold being used by the system. |
Conditions for Clearing the MIL/DTC
| • | Using a scan tool. |
| • | A current DTC will clear when the diagnostic runs and does not fail. |
| • | IPM battery voltage is interrupted. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Perform the Body Control Module Diagnostic Symptom Check before continuing with the diagnosis of this DTC.
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This test allows recalibration of the actuator by the scan tool.
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This step determines if the instrument panel integration module (IPM) is malfunctioning.
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This step determines if the actuator is operational.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the IPM/DIM/RIM diagnostic system check performed? | -- | Go to Step 2 | ||
Is the difference between the minimum counts and the maximum counts within the specified range? | 150-220 counts | Go to Step 3 | Go to Step 4 | |
3 |
Does the module function thru its Full Range? | -- | Go to Step 4 | Go to Step 18 |
4 |
Is the voltage measured at the specified value? | 5 V | Go to Step 5 | Go to Step 9 |
5 | Measure voltage at terminal 5, CKT 141 (BRN). Is the voltage measured at the specified value? | 10 - 15 V | Go to Step 6 | Go to Step 9 |
6 | Measure voltage between terminal 7, CKT 1791 (YEL) and terminal 5, CKT 141 (BRN). Is the voltage measured at the specified value? | 10 - 15 V | Go to Step 7 | Go to Step 9 |
7 | Measure voltage at terminal 6, CKT 1646 (DK BLU). Is the voltage measured at the specified value? | 2.5 V | Go to Step 8 | Go to Step 9 |
8 | Measure voltage at terminal 9, CKT 1236 (WHT/BLK). Is the voltage measured at the specified value? | 5 V | Go to Step 9 | Go to Step 11 |
9 | Inspect the circuits for an open, or short conditions. Did you find an open or a short? | -- | Go to Step 10 | Go to Step 11 |
10 | Repair the open or short condition. Is the repair complete? | -- | Go to Step 21 | -- |
View the actuator data on the scan tool. Is the actuator actual data displayed on the scan tol at the specified value? | 5 V or 255 counts | Go to Step 12 | Go to Step 20 | |
12 | Short terminal 6 CKT 1646 (DK BLU) to GND. Is the actuator actual data displayed on the scan tool at the specified value? | 0 V or 0 counts | Go to Step 13 | Go to Step 20 |
13 | Connect the electrical connector to the actuator. Is the voltage within the specified range? | 5 V or 255 counts | Go to Step 19 | Go to Step 14 |
Use the scan tool in order to move the actuator to the hot position and the cold position. Does the actuator move in both directions? | -- | Go to Step 15 | Go to Step 16 | |
15 | Did the actuator actual position feedback change? | -- | Go to Step 21 | Go to Step 19 |
16 | Short terminal 10, CKT 705 (GRY) to terminal 9, CKT 1236 (WHT/BLK). Did the actuator move? | -- | Go to Step 17 | Go to Step 18 |
17 | Did the actuator actual position feedback change? | -- | Go to Step 21 | Go to Step 19 |
18 | Short terminal 7, CKT 1791 (YEL) to terminal 9, CKT 1236 (WHT/BLK). Did the actuator move? | -- | Go to Step 17 | Go to Step 19 |
19 | Replace the actuator. Refer to Air Mix Actuator Replacement - Passenger in HVAC Systems with A/C-Automatic. Is the repair complete? | -- | Go to Step 21 | -- |
20 | Replace the IPM. Refer to Body Control Module Replacement in HVAC Systems with A/C-Automatic. Is the repair complete? | -- | Go to Step 21 | -- |
21 | Confirm proper operation of the A/C system. Does the system operate normally? | -- | -- |
