Circuit Description
The transfer case motor is a bi-directional, permanent magnet, D.C. motor. When energized through Motor Control A or Motor Control B, the ground is provided by the opposing Motor Control circuit and then grounded through the transfer case shift control module ground circuit The motor, through a series of gears, rotates a shaft which moves the mode and range forks to shift the Transfer Case between 4H, AUTO 4WD, 2H, N, and 4L ranges.
This DTC detects an open in the Motor Control A or Motor Control B circuits, or an open motor.
Conditions for Setting the DTC
| • | The system will test the motor circuits by checking for unwanted voltage. |
| • | Then, the system supplies voltage on each of the motor circuits and reads the voltage back on the other circuit. |
| • | If the system detects a problem with the circuits, the DTC is logged. The transfer case shift control module senses a low voltage return in the Motor Control A or Motor Control B circuits when a high voltage is expected. |
Action Taken When the DTC Sets
| • | All shifting will be disabled. |
| • | The SERVICE 4WD indicator will be latched on for the remainder of the current ignition cycle. |
Conditions for Clearing the DTC
| • | The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | History DTCs can be cleared using a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Listen for an audible motor noise when the encoder motor operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests the for a higher than normal resistance in the Motor Control A and B circuits and through the module.
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Tests the Motor Control A circuit for an open or high resistance.
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Tests the Motor Control B circuit for an open or high resistance.
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Tests for continuity across the motor circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | |
Does the encoder motor turn ON and OFF? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Is the resistance reading greater than the specified value? | 2 ohms | Go to Step 4 | Go to Step 6 | |
Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 5 | |
Test the Motor Control B circuit harness connector for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 8 | |
Test the resistance across the motor circuit. Were the readings within the specified values? | 0.5-35 ohms | Go to Step 8 | Go to Step 7 | |
7 | Replace the encoder motor. Refer to Transfer Case Motor/Encoder Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
8 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the repair complete? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
