
Typical TP sensor
VSS Sensor
The Vehicle Speed (VSS) Sensor input is used by the PCM to determine vehicle speed.
The VSS generates a signal that increases in frequency proportionate to vehicle speed.
The PCM has a base frequency stored in memory for a distance of one mile. By
comparing the input and stored value, the PCM calculates vehicle speed.
VSS types include: photo-optic, permanent magnet generators or hall effect technology.
The PCM may use other sensors on the vehicle (ABS Wheel Speed) to validate VSS
operation.
VSS information is used to calculate vehicle loads including: torque converter application,
cruise control, fuel cutoff/speed governance strategies, instrument panel speedometer and
more.
Modified drivetrain components such as final gear sets and/or tires can alter VSS input
values to the PCM. Improper signals can alter Torque Converter Clutch (TCC) application,
shift points, cruise control operation as well as many other systems relying on vehicle
speed input.
Summary of Contents for TrailBlazer
Page 1: ......
Page 26: ...Fig 3 Typical body and undervehicle maintenance locations Refer to chart for descriptions ...
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Page 175: ...Spring free length check Valve spring squareness check ...
Page 192: ...Front of piston mark ...
Page 361: ...5 3L Engine Except Saab Underhood Fuse Block 2003 2005 Early Production ...
Page 469: ...Removing the outer band from the CV boot Removing the inner band from the CV boot ...
Page 470: ...Removing the CV boot from the joint housing Clean the CV joint housing prior to removing boot ...
Page 471: ...Removing the CV joint housing assembly Removing the CV joint ...
Page 472: ...Inspecting the CV joint housing Removing the CV joint outer snap ring ...
Page 473: ...Checking the CV joint snap ring for wear CV joint snap ring typical ...
Page 474: ...Removing the CV joint assembly Removing the CV joint inner snap ring ...
Page 475: ...Installing the CV joint assembly typical ...
Page 553: ...9 Torque the lug nuts to specification 10 Lower the vehicle ...
Page 556: ...Toe in Frame Misalignment Frame misalignment ...
Page 588: ...Bleeding caliper ...
Page 624: ...Manifold gauge set components Refrigerant recovery recycling station ...
Page 676: ...A C Specifications ...
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