Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Transmission General Description (See: Transmission and Drivetrain/Automatic Transmission/Transaxle/Description and
Operation/6L45/6L50/6L80/6L90 - Automatic Transmission/Transmission General Description)
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
Special Tools
J 35616 - GM-Approved Terminal Test Kit
Circuit/System Verification
Note: It may be necessary to drive the vehicle slightly forward to engage 4LO on the transfer case.
Verify the scan tool displays Disabled when you select 4HI and Enabled when you select 4LO.
Circuit/System Testing
1. Remove connector from the transfer case control module. With ignition ON and engine OFF, observe with the scan tool the 4WD Low
parameter.
锟斤拷If the scan tool indicates Enabled, test the 4WD Low signal circuit for a short to ground.
2. Using the J 35616 - GM-approved terminal test kit, install a fused jumper between the 4WD low signal circuit and ground at the transfer case
control module connector.
锟斤拷If the scan tool 4WD Low parameter indicates Enabled when grounded, replace the transfer case control module.
3. Test the 4WD Low signal circuit for an open.
锟斤拷Fix the open in the 4WD Low circuit.
4. Replace the ECM.
Component Testing
Verify the 4WD Low parameter on scan tool while cycling the 4WD Low switch.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the repair.
Control Module References (See: Testing and Inspection/Programming and Relearning)for replacement, setup, and programming
P2797
DTC P2797
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
