What is a speed pulse wire?
Your vehicle’s cruise control uses the VSS wire to determine the vehicle’s speed — it serves the same function for the navigation system. The VSS wire sends a series of pulses (from 800 to just over 1,000 per mile) only when the vehicle is in motion.
Can a bad wheel speed sensor cause transmission problems?
A failing speed sensor will directly impact the transmission operation, leading to delayed shifting and limited gear choices, while numerous other sensors can have similar detrimental effects.
What is the function of speed sensor?
The vehicle speed sensor (VSS) measures transmission/transaxle output or wheel speed. The ECM uses this information to modify engine functions such as ignition timing, air/fuel ratio, transmission shift points, and to initiate diagnostic routines.
What is the function of the transmission speed sensor?
The speed sensor detects a gear or target wheel in the transmission and generates an electric digital signal proportional to the speed of rotation. The transmission controls use this information to modify various transmission functions such as shift points and perform diagnostic tests.
How is the speed sensor attached to the car?
In a representative vehicle speed measurement system, the vehicle speed information is mechanically coupled to the speed sensor by a flexible cable coming from the driveshaft, which rotates at an angular speed proportional to vehicle speed.
How is the number of pulses generated per second related to vehicle speed?
The number of pulses generated per second is proportional to the number of slots in the disk and the vehicle speed: where f is the frequency in pulses per second, N is the number of slots in the sensor disk, V is the vehicle speed, K is the proportionality constant that accounts for differential gear ratio and wheel size.
How does a speed sensor work with an Excitor?
Speed sensor and excitor (Fig. 11.40) The speed sensor uses the variable reluctance magnetic sensing principle, whereby a cylindrical permanent magnetic core with a coil wire wound around it, mounted on the stationary hub carrier, axle casing or back plate, produces a magnetic field (flux) which overlaps the rotating excitor ring.
How is the frequency of a speed sensor determined?
A number of teeth or slots are arranged radially which, with the speed of rotation of the road wheel, determine the frequency of the signal transmitted to the electronic-control unit. As the wheel and excitor revolve, the teeth and gaps or ribs and slots of the excitor pass through the magnetic field of the sensor.