Circuit Description
The transfer case shift control module senses rear slip. After several attempts of applying torque to the front wheels, by activating the encoder motor, the transfer case still sees a difference in speed between the front propshaft speed sensor and rear propshaft speed sensor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0374 General System Malfunction
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The system voltage is 9-18 volts. |
Conditions for Setting the DTC
The transfer case shift control module is unable to correct sensed wheel slip for 10 consecutive seconds.
Action Taken When the DTC Sets
| • | All shifts to AUTO 4WD Mode are disabled. If the current mode is AUTO 4WD, the system will not allow any further adaptive events, such as correcting slip. |
| • | The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle. |
Conditions for Clearing the DTC
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | Use a scan tool in order to clear history and current DTCs. |
Diagnostic Aids
If DTCs C0300 or C0305 have set, diagnose these DTCs first as they may cause DTC C0374 to set falsely. Refer to DTC C0300 or DTC C0305 .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the rear propshaft speed sensor and wiring are operating properly.
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This step determines if the front propshaft speed sensor and wiring are operating properly.
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This step determines if the motor control A or motor control B circuits are shorted to ground within the encoder motor.
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This step tests the integrity of the motor windings.
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This step tests the motor control A and motor control B circuits for an open, short to ground, or high resistance between the encoder motor and the transfer case shift control module.
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This step determines whether the transfer case is mechanically functioning properly.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Transfer Case Control Schematics Connector End View Reference: Transfer Case Control Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does the RPM value vary or become intermittent while driving at a steady speed? | -- | Go to DTC C0300 | Go to Step 3 | |
Does the RPM value vary or become intermittent while driving at a steady speed? | -- | Go to DTC C0305 | Go to Step 4 | |
Is motor control A or motor control B shorted to ground? | -- | Go to Step 9 | Go to Step 5 | |
|
Important: Use test leads designed for this connector and make firm contact with the leads.
Is the encoder motor within the specified values? | 0.3-35 ohms | Go to Step 6 | Go to Step 9 | |
Test the motor A and motor B control circuits for a short to ground, a short to voltage, an open, or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 | |
Does the clutch hold the propshaft and prevent it from being turned? | -- | Go to Step 9 | Go to Step 8 | |
8 | Remove the transfer case and overhaul. Refer to Transfer Case Disassemble in Transfer Case - NVG 246-NP8 Unit Repair. Did you complete the repair? | -- | Go to Step 11 | -- |
9 | Replace the transfer case encoder motor. Refer to Transfer Case Encoder Motor Replacement . Did you complete the repair? | -- | Go to Step 11 | -- |
10 | Replace the transfer case shift control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the repair? | -- | Go to Step 2 | -- |
11 |
Does the DTC set? | -- | Go to Step 10 | System OK |
