Circuit Description
The transfer case motor is a bi-directional, permanent magnet, DC motor. When energized through motor control A or motor control B, the ground is provided by the opposing motor control circuit, 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 a short to voltage in the motor control A or motor control B circuits, or a shorted motor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0309 Motor A/B Circuit High
Conditions for Running the DTC
| • | The ignition in ON. |
| • | The system voltage is 9-16 volts. |
Conditions for Setting the DTC
| • | The system tests the motor circuits by reading the voltage on each circuit. |
| • | If the system detects a condition with the circuits, the DTC is logged. |
| • | The transfer case shift control module senses a high voltage in the motor control A or motor control B circuits when a low voltage is expected. |
Action Taken When the DTC Sets
| • | The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle. |
| • | All shifting is disabled. |
Conditions for Clearing the DTC
| • | The transfer case shift control module clears the DTC if the condition for setting the DTC no longer exists. |
| • | A history DTC clears 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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Tests for proper voltage and grounds.
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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 Motor Feed A or the transfer case shift control module for a short to voltage.
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Tests Motor Feed B or the transfer case shift control module for a short to voltage.
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Tests Motor Feed A circuit for a short to voltage.
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Tests Motor Feed B circuit for a short to voltage.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics | ||||
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | |
Check the transfer Case shift control module for faulty power or grounds. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 3 | |
Does the encoder motor turn ON and OFF? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 | |
Is the voltage reading within the specified value? | 0-0.2 V | Go to Step 5 | Go to Step 6 | |
Connect a DMM between the Motor Control B circuit harness connector and ground at the transfer case. Is the voltage reading within the specified value? | 0-0.2 V | Go to Step 8 | Go to Step 7 | |
Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 8 | |
Was the condition found and corrected? | -- | Go to Step 9 | Go to Step 8 | |
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 |
