2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 892

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 892

DTC C0321

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 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

The transfer case shift control module controls the transfer case lock solenoid.

The transfer case lock solenoid is released by being energized. This is accomplished by grounding the lock solenoid control circuit during mode

shifts, and 4WD Auto mode. Locking action is applied when power or ground are taken away from the lock solenoid, the transfer case motor is

prevented from moving. The system is capable of providing a 2WD HI, 4WD Auto, or 4WD HI lock-up without the need of additional vehicle

power to hold the transfer case in these positions.

This DTC detects an open lock solenoid coil, open motor lock control circuit, or an open battery positive voltage circuit, or a short to voltage or

ground on the lock solenoid control circuit.

Conditions for Running the DTC

* Ignition ON

* System voltage 10.5-18 V

Conditions for Setting the DTC

* The system tests the lock solenoid circuits by checking for unwanted voltage.

* The underhood fuse block supplies B+ on the battery positive voltage circuit and reads the voltage back on the lock solenoid control 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

C0321 01 and C0321 04

* Shifts allowed. Clutch engages only if slip is detected.

* The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.

C0321 02 and C0321 08

* Normal operation.

* The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.

Conditions for Clearing the DTC