2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 884
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
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 encoder motor (TCEM) 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 (TCCM)
ground circuit, the TCEM, through a series of gears, rotates the transfer case control actuator shaft which moves the transfer case two/four wheel
drive actuator cam and transfer case high/low shift fork to shift the transfer case between the following modes or ranges:
* 2WD HI
* 4WD Auto
* 4WD HI
Conditions for Running the DTC
* Ignition ON
* System voltage 10.5-18 V
Conditions for Setting the DTC
* The TCCM tests the motor circuits by checking for unexpected voltage.
* The TCCM supplies voltage on each of the motor circuits and reads the voltage back on the other circuit.
* If the TCCM detects a low voltage return when a high voltage is expected, or a high voltage return when a low voltage is expected, the DTC
is logged.
* The fault must remain current for 1 second to set the DTC.
Action Taken When the DTC Sets
* All shifting is disabled.
* The mode light shall flash upon a requested mode change and then return to the current mode.
* The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
Conditions for Clearing the DTC
* The TCCM clears the DTC once the conditions for setting the DTC are no longer present.
* A history DTC clears after 40 consecutive warm-up cycles without a fault present.
* History DTCs can be cleared using a scan tool.
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.
* The default actions for C0321 may set C0306.
* EL-49741 - harness is a good source for 9 V.
* EL-49742 - harness is a good source for B+ and ground.
* The transfer case fill and drain plugs are a good source for ground.
