2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2070
瀚慖f greater than the specified range, replace the hood ajar switch.
4. With the switch in the hood open position, test for infinite resistance between the ground terminal C and the signal terminal B.
瀚慖f not infinite, replace the hood ajar switch.
5. Test for less than 2.0 ohms between the ground terminal C and the signal terminal A.
瀚慖f greater than the specified range, replace the hood ajar switch.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Hood Primary and Secondary Latch Replacement (See: Body and Frame/Doors, Hood and Trunk/Hood/Hood Latch/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, programming and setup
P279A
DTC P279A
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 P279A
- Four Wheel Drive (4WD) High Range Performance
Circuit/System Description
The engine control module (ECM) monitors the state of the 4WD range 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. 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 then this DTC is set.
* The ECM has detected 32 fail counts out of 400 samples.
Action Taken When the DTC Sets
DTC P279A is a Type C DTC.
Conditions for Clearing the DTC
* DTC P279A 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
