Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Vehicle Speed Sensor (VSS)
VSS is located on transmission extension housing (2WD models) or on transfer case extension housing (4WD models). PCM uses VSS to determine vehicle speed and distance traveled.
VSS is an 8-pole switch which provides a pulse or switching rate, proportional to vehicle speed, to the PCM. By comparing the number of pulses to time elapsed, the PCM determines vehicle speed and distance traveled. VSS generates 8 pulses per sensor revolution. This signal, along with a closed throttle signal from the TP sensor, indicates a closed throttle deceleration to the PCM.
Under deceleration conditions, PCM adjusts the Idle Air Control (IAC) motor to maintain desired MAP value. During idle (vehicle stopped), the PCM receives no signal from the VSS. The PCM adjusts the IAC motor to maintain a desired engine speed.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.