C0379

DTC C0379

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptor
DTC C0379
- Front Axle System Malfunction

Circuit/System Description

The front axle control circuit consists of an electric motor actuator, which engages and disengages the front axle. The front axle actuator motor consists of a permanent magnetic motor, a worm gear controlled plunger, a front axle switch and an electronic control circuit, all within the actuator assembly.

The front axle actuator consists of the following circuits:

* The front axle control circuit, which is also connected to the transfer case shift control module
* The front axle switch circuit, which is also connected to the transfer case shift control module
* An ignition 3 voltage circuit
* A ground circuit

When a shift to AUTO 4WD, 4HI, or 4LO is requested, the transfer case shift control module engages the front axle by grounding the front axle control circuit through a current limiting driver.

This DTC detects a short to ground, short to voltage or an open circuit.

Conditions for Running the DTC

* The ignition is ON.
* System voltage is 9-18 volts.

Conditions for Setting the DTC

* The transfer case shift control module monitors the state of the front axle switch. The transfer case shift control module reads back the front axle switch circuit for a high and low voltage. The DTC sets if this circuit is high when a low voltage is present or when the circuit is low when a high voltage is present for 10 seconds.
* The DTC sets if this circuit is high when a low voltage is present or when the circuit is low when a high voltage is present for 10 seconds.

Action Taken When the DTC Sets

The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.

Conditions for Clearing the DTC

* The transfer case shift control module clears the DTC if the condition for setting the DTC is not currently present.
* A history DTC clears after 100 consecutive ignition cycle without a fault present.
* History DTCs can be cleared using a scan tool.

Reference Information
Schematic Reference

Transfer Case Control Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Transfer Case Description and Operation (NVG 226-NP8 - Transfer Case)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.