Located on the transmission case, within the rear differential assembly or inside the ABS system, the vehicle speed sensor reads the speed of the wheel rotation on a vehicle while driving. The sensor also aids the vehicle sustain stability while driving by instructing the computer when to release pressure to a wheel while using the ABS.
A type of tachometer, the part consists of a toothed ring and pickup. The speed sensor reads the rotational speed of the reluctor wheel, positioned within the transmission. Speed sensors within the differential use a trigger wheel mounted in conjunction with the ring gear to accomplish the same tasks as those performed by the transmission-mounted version.
Facts to Note:
The mechanic will run a diagnostic on the vehicle to find the exact cause of the problem.
A faulty speed sensor sometimes shows symptoms similar to a failing transmission.
The mechanic will check the transmission.
Some vehicles use the information from the sensor to help determine ride height, a feature in newer vehicles.
The mechanic will check all connections to make sure everything remains connected correctly.
How to Fix:
The speed sensor is confirmed that it needs to be changed. The vehicle is lifted and held on jack stands.
The speed sensor is situated in the rear axle. The speed sensor is detached from the rear axle housing.
The new speed sensor is fitted into the axle housing.
The speed sensor connector is connected. The vehicle is removed from the jack stands.
The vehicle is road tested and scanned for proper operation of the speed sensor.
When changing the vehicle speed sensor, the mechanic will first run a diagnostic to make sure that the problem does not lie with the transmission instead.
Replace a defective speed sensor as soon as you can to avoid further damages on your vehicle. The speed sensor also controls the anti-lock braking system. Driving with a bad speed sensor usually causes the ABS to malfunction and can lead to loss of braking power and/or an accident. The speed sensor equally affects the transmission, causing it to perform intermittently.
Common symptoms indicating you may need to change the Speed Sensor:
Odometer does not work
Speedometer stops functioning or performs intermittently
Cruise control fails to function properly
Transmission hesitates to shift gears or shifts roughly, sometimes revving higher as the driver shifts gears
Transmission jumps gears
Vehicle idles incorrectly
Vehicle suddenly loses power
Fuel efficiency drops
Check Engine Light, brake, or anti-lock warning lamps come on
Importance of this service:
While vehicle owners can get away with not changing a vehicle speed sensor initially, they can expect the vehicle’s usability to only worsen over time. Owners want to refrain from waiting until the part goes out completely, which could cause critical vehicle systems, such as the speedometer and anti-lock brakes, to stop functioning entirely.