Diagnostic Aids
* Inspect the rear internal gear teeth for damage.
* Visually inspect the VSS for cracks or damage.
* Ensure the VSS is properly torqued to the transfer case housing.
* This diagnostic relates to the VSS located in the transfer case and not the OSS located within the transmission.
Reference Information
Schematic Reference
* Transfer Case Control Schematics (See: Transmission and Drivetrain/Transfer Case/Diagrams/Electrical Diagrams/MP 3023/3024-NQH -
Transfer Case)
* Engine Controls Schematics (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Transfer Case Description and Operation (See: Transmission and Drivetrain/Transfer Case/Description and Operation/MP 3023/3024-NQH -
Transfer Case/Transfer Case Description and Operation)
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. Raise and support the drive wheels.
2. Start and idle the engine.
3. Place the transmission in DRIVE.
4. Monitor VSS on the scan tool under engine data.
5. The VSS on the scan tool should be greater than 100 RPM.
Circuit/System Testing
1. Measure the resistance between the VSS high signal circuit and the VSS low signal circuit. The resistance should be between 1,420-2,140
ohms.
锟斤拷If the value is greater than 2,140 ohms, test the VSS high signal circuit and the VSS low signal circuit for an open.
锟斤拷If the value is less than 1,420 ohms, test the VSS high signal and the VSS low signal circuits for a shorted together condition.
2. Measure the resistance of the VSS high signal circuit to ground. The resistance should be greater than 10M ohms.
锟斤拷If the value is less than 10M ohms, repair the short to ground.
3. Measure the resistance between the VSS low signal circuit and ground. The resistance should be greater than 10M ohms.
锟斤拷If the value is less than 10M ohms, repair the short to ground.
4. Reconnect the ECM connector. Disconnect the VSS connector. Ignition ON, test the VSS high signal circuit for a short to voltage.
锟斤拷If all circuits/connections test normal, test or replace the VSS.
5. If all previous steps for circuit checking and VSS replacement have been made and all component testing has been performed and the
