2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 884

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.