Sierra 2500 Denali 2WD V8-6.0L (2011)
Vehicle Speed Sensor: Testing and Inspection
Tremec 5-Speed (TZ0) - Manual Transmission
Vehicle Speed Sensor Diagnosis
Diagnostic Instructions
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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.
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Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
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Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure Instructions
)provides an overview of each diagnostic category.
Circuit/System Description
The vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The VSS is a permanent magnet
generator that is mounted to the transmission and produces a pulsing voltage. The AC voltage amplitude and frequency increases with vehicle speed. The
ECM converts the pulsing voltage into km/h (mph). The ECM supplies the VSS signal to the following components:
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The instrument panel for speedometer and odometer operation
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The cruise control module
Reference Information
Schematic Reference
Manual Transmission Schematics (See: Transmission and Drivetrain/Manual Transmission/Transaxle/Diagrams/Electrical Diagrams/Tremec 5-Speed
(TZ0) - Manual Transmission)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)
Description and Operation
Manual Transmission Description and Operation (See: Transmission and Drivetrain/Manual Transmission/Transaxle/Description and
Operation/Tremec 5-Speed (TZ0) - Manual Transmission)
Electrical Information Reference
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Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
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Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Connector
Repairs/Connector Repairs)
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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)
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Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning/Control Module References)for scan tool information.
Circuit/System Verification
1. Raise the vehicle off the ground.
2. Support the rear axle assembly so that the propeller shaft is at the normal drive line angle.
3. Start and idle the engine.
4. Place the transmission in second gear and release the clutch pedal.
5. Monitor VSS parameter on the scan tool. The VSS parameter should increase as the drive wheel speed increases, and match the speedometer
display on the instrument cluster.
6. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as
this may result in an unnecessary part replacement. Refer to 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).
Circuit/System Testing
