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 P279B is a Type C DTC.
Conditions for Clearing the DTC
* DTC P279B 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)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information.
Circuit/System Verification
1. Start the engine.
2. Let the engine run for 1 minute, then turn the key OFF for 30 seconds.
3. Retest for DTC P279B.
Circuit/System Testing
1. Observe the 4WD Signal in the ECM Data List. The 4WD signal should display Enabled when you shift into 4WD and Disabled when you
shift into 2WD.
锟斤拷If the scan tool display does not match the transfer case range switch state, repair the transfer case system. Refer to Diagnostic System
Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System Check - Vehicle).
锟斤拷If the scan tool matches the transfer case range switch state, continue with testing.
2. Program the ECM with the latest software version and retest for DTCs.
锟斤拷If the DTC resets, replace the ECM.
