Vehicle Speed Sensor: Description and Operation

1997 Ford Escort L4-122 2.0L SOHCSECTION Description and Operation

Vehicle Speed Sensor (VSS):






PURPOSE
The Vehicle Speed Sensor (VSS) generates a waveform with a frequency that is proportional to the speed of the vehicle.

OPERATION

How The Signal Is Generated
If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency.

How The Signal Is Used
The Powertrain Control Module (PCM) uses the frequency signal generated by the VSS to control such parameters as fuel injection, ignition timing, transmission / transaxle shift scheduling and torque converter clutch scheduling.

CONSTRUCTION
The VSS is a variable reluctance or hall effect type sensor.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.