NVG 126-NP4 - Transfer Case

DTC C0305

Diagnostic Instructions

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



DTC Descriptor
DTC C0305
- Front Speed Sensor Malfunction




Circuit/System Description

The front propshaft speed sensor is a permanent magnet generator. The permanent magnet generator produces a pulsing AC voltage. The AC voltage level and number of pulses increase as speed increases. The transfer case shift control module converts the pulsating AC voltage to a propshaft RPM which is used for calculations, and to monitor the difference between the front and rear propshaft speed. It is also used in the AUTO, Adapt mode of operation to determine the amount of slip and the percent of torque to apply to the front axle. The module only looks at this input when the vehicle is in AUTO, Adapt mode, 4H, and 4L ranges. The propshaft RPM can be displayed with a scan tool.


This DTC detects an open , short to ground, short to voltage or faulty sensor.


Conditions for Running the DTC

* The ignition is ON.
* System voltage is 9-18 volts.
* Vehicle speed exceeds 16 km/h (10 mph).



Conditions for Setting the DTC

The system logs the DTC if the front propshaft input indicates a speed of less than 16 RPM for 30 seconds while all of the following are true:

* The transmission is NOT in PARK/NEUTRAL.
* The engine is running.
* The rear propshaft speed exceeds 512 RPM.
* Vehicle Speed On Class 2 Data bus exceeds 16 km/h (10 mph).



Action Taken When the DTC Sets

* All shifts to AUTO, Adapt mode are disabled. If the current mode is AUTO, the system does not allow any further adaptive events, correct slip.
* The SERVICE AWD 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 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.



Reference Information
Schematic Reference

Transfer Case Control Schematics (NVG 126-NP4 - Transfer Case)
Connector End View Reference

Component Connector End Views
Description and Operation

Transfer Case Description and Operation (NVG 126-NP4 - Transfer Case)
Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs

Scan Tool Reference

* Scan Tool Output Controls (Scan Tool Output Controls)
* Scan Tool Data List (Scan Tool Data List)
* Scan Tool Data Definitions (Scan Tool Data Definitions)



Circuit/System Verification

TBD


Circuit/System Testing

TBD


Component Testing

TBD


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Repair Verification

TBD