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Chevrolet Silverado / GMC Sierra. Manual - part 2915
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC C0306 02
Motor A or B Circuit Short to Ground
DTC C0306 05
Motor A or B Circuit Short to Battery or Open
Diagnostic Fault Information
Circuit/System 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 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 the following modes or ranges:
2HI
4HI
4LO
AUTO 4WD
Neutral
This DTC detects an open, short to voltage, or short to ground in the motor control A or motor
control B circuits, or an open, or short to ground inside the motor.
Conditions for Running the DTC
The ignition is ON.
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Invalid
Motor A or B Circuit
DTC C0306
02
DTC C0306
05
DTC C0306
05
-
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
System voltage is 10.5-18 volts.
Conditions for Setting the DTC
The system tests 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 condition 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.
The fault must remain current for 30 seconds to set the DTC.
Action Taken When the DTC Sets
All shifting is disabled.
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 40 consecutive warm up cycles without a fault present.
History DTCs can be cleared using a scan tool.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Wiring Repairs
Scan Tool Reference
Scan Tool Data List
Scan Tool Data Definitions
Diagnostic Aids
It is possible to have windings inside the motor shorted to the case resulting in a short to ground
causing this DTC to set.
Circuit/System Testing
The motor A control and motor B circuits need to be checked for shorts to ground, opens, high
resistance, and shorts to voltage by following the below listed steps.
1. With the ignition off disconnect connector X3 from the transfer case control module, and
also disconnect the connector at the transfer case actuator.
With a DMM check the motor A control and motor B control circuits for an open,
high resistance, or short to ground and repair as necessary. If all check good go to the
next step
2. Connect X3 at the transfer case control module and turn on the ignition.
Check to motor A control and motor B control circuits for a short to voltage. If the
circuits shows to indication of a short to voltage go to component testing.
Component Testing
1. Turn the ignition of and check the motor windings for an internal short to ground inside the
motor by probing either the motor A control pin and taking the other lead to ground, or the
same can be done using motor B control pin. Motor control A is pin A and motor B control
is pin D.
If the DMM indicates and short to ground replace the transfer case actuator. If nothing
is found continue to the next step.
2. With a DMM check the resistance of the motor windings by probing pin A and pin D on the
transfer case actuator.
The DMM should indicate 0.3-40 ohms, if it does not replace the transfer case actuator
and complete the motor learn procedure. If the actuator is within specifications then
replace the transfer case control module, program, and complete the motor learn
procedure.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TCSCM replacement, setup, and programming
Transfer Case High/Low Clutch Reset
Transfer Case Two/Four Wheel Drive Actuator Replacement
DTC C0321
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 C0321 01
Transfer Case Lock Circuit Short to Battery
DTC C0321 02
Transfer Case Lock Circuit Short to Ground
DTC C0321 04
Transfer Case Lock Circuit Open
DTC C0321 08
Transfer Case Lock Circuit Signal Invalid
Diagnostic Fault Information
Circuit/System Description
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Invalid
Transfer Case Lock Circuit
DTC C0321
02
DTC C0321
04
DTC C0321
01
DTC C0321
08
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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