2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2073
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming.
P279C
DTC P279C
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 Descriptor
DTC P279C
- Four Wheel Drive (4WD) Neutral Range Performance
Circuit/System Description
The engine control module (ECM) monitors the state of the 4WD signal message, if equipped, over the GMLAN communication bus. The ECM
uses this message to determine motor torque required and transmission shifting. There are no external circuits involved.
Conditions for Running the DTC
The engine is running for greater than 5 seconds. Vehicle speed is less than 200 km/h (124 mph) for greater than 5 seconds.
Conditions for Setting the DTC
* The ECM uses two ways to determine if the transfer case is in 4 low, 4 high, and neutral. The first way is to compare the transmission output
speed sensor to the transfer case speed sensor in order to calculate transfer case range. The second way is to use a LAN message sent by the
transfer case shift control module. If the first way and second way of determining this does not match while in 4 high, 4 low, or neutral, then
this DTC is set. This DTC sets if the gear ratio for 4 high or 4 low is indicated by the speed sensors.
* The ECM has detected 32 fail counts out of 400 samples.
Action Taken When the DTC Sets
DTC P279C is a Type C DTC.
Conditions for Clearing the DTC
* DTC P279C is a Type C DTC.
* When attempting to set ECM internal DTCs, run the engine for at least 1 minute, and then shut the engine off for 30 seconds. Following this
procedure will allow for a complete ECM shutdown. Program the ECM with the latest software version and retest the DTC to see if the DTC
resets.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (See: Transmission and Drivetrain/Automatic Transmission/Transaxle/Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
