2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 888

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 888

MP 3023/3024-NQH - Transfer Case

DTC C0306

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 which becomes 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 in order to shift the transfer case between the following modes or ranges:

* 2WD HI

* 4WD Auto

* 4WD HI

* 4WD LO

* Neutral

Conditions for Running the DTC

* Ignition ON.

* System voltage 10.5-18 V.

* Encoder motor not moving.

* Circuit checked either 5-35 seconds after key ON or 5-35 seconds after shift.

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.